media: adv7604: mark unused functions as such

There are several unused helper macros there, meant to parse some
fields. As those actually help to document the hardware, the
better is to keep them.

However, it generates clang warnings with W=1, causing build to
break with CONFIG_WERROR.

So, add __always_unused to fix such warnings.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/i2c/adv7604.c

@@ -398,14 +398,14 @@ static inline int io_write_clr_set(struct v4l2_subdev *sd, u8 reg, u8 mask,
 	return io_write(sd, reg, (io_read(sd, reg) & ~mask) | val);
 }
 
-static inline int avlink_read(struct v4l2_subdev *sd, u8 reg)
+static inline int __always_unused avlink_read(struct v4l2_subdev *sd, u8 reg)
 {
 	struct adv76xx_state *state = to_state(sd);
 
 	return adv76xx_read_check(state, ADV7604_PAGE_AVLINK, reg);
 }
 
-static inline int avlink_write(struct v4l2_subdev *sd, u8 reg, u8 val)
+static inline int __always_unused avlink_write(struct v4l2_subdev *sd, u8 reg, u8 val)
 {
 	struct adv76xx_state *state = to_state(sd);
 
@@ -439,14 +439,14 @@ static inline int infoframe_read(struct v4l2_subdev *sd, u8 reg)
 	return adv76xx_read_check(state, ADV76XX_PAGE_INFOFRAME, reg);
 }
 
-static inline int infoframe_write(struct v4l2_subdev *sd, u8 reg, u8 val)
+static inline int __always_unused infoframe_write(struct v4l2_subdev *sd, u8 reg, u8 val)
 {
 	struct adv76xx_state *state = to_state(sd);
 
 	return regmap_write(state->regmap[ADV76XX_PAGE_INFOFRAME], reg, val);
 }
 
-static inline int afe_read(struct v4l2_subdev *sd, u8 reg)
+static inline int __always_unused afe_read(struct v4l2_subdev *sd, u8 reg)
 {
 	struct adv76xx_state *state = to_state(sd);
 
@@ -479,14 +479,14 @@ static inline int rep_write_clr_set(struct v4l2_subdev *sd, u8 reg, u8 mask, u8
 	return rep_write(sd, reg, (rep_read(sd, reg) & ~mask) | val);
 }
 
-static inline int edid_read(struct v4l2_subdev *sd, u8 reg)
+static inline int __always_unused edid_read(struct v4l2_subdev *sd, u8 reg)
 {
 	struct adv76xx_state *state = to_state(sd);
 
 	return adv76xx_read_check(state, ADV76XX_PAGE_EDID, reg);
 }
 
-static inline int edid_write(struct v4l2_subdev *sd, u8 reg, u8 val)
+static inline int __always_unused edid_write(struct v4l2_subdev *sd, u8 reg, u8 val)
 {
 	struct adv76xx_state *state = to_state(sd);
 
@@ -570,7 +570,7 @@ static inline int hdmi_write_clr_set(struct v4l2_subdev *sd, u8 reg, u8 mask, u8
 	return hdmi_write(sd, reg, (hdmi_read(sd, reg) & ~mask) | val);
 }
 
-static inline int test_write(struct v4l2_subdev *sd, u8 reg, u8 val)
+static inline int __always_unused test_write(struct v4l2_subdev *sd, u8 reg, u8 val)
 {
 	struct adv76xx_state *state = to_state(sd);
 
@@ -601,14 +601,14 @@ static inline int cp_write_clr_set(struct v4l2_subdev *sd, u8 reg, u8 mask, u8 v
 	return cp_write(sd, reg, (cp_read(sd, reg) & ~mask) | val);
 }
 
-static inline int vdp_read(struct v4l2_subdev *sd, u8 reg)
+static inline int __always_unused vdp_read(struct v4l2_subdev *sd, u8 reg)
 {
 	struct adv76xx_state *state = to_state(sd);
 
 	return adv76xx_read_check(state, ADV7604_PAGE_VDP, reg);
 }
 
-static inline int vdp_write(struct v4l2_subdev *sd, u8 reg, u8 val)
+static inline int __always_unused vdp_write(struct v4l2_subdev *sd, u8 reg, u8 val)
 {
 	struct adv76xx_state *state = to_state(sd);