media: i2c: tc358746: fix ignoring read error in g_register callback

Currently we ignore the return value of tc358746_read() and return
alawys return 0 which is wrong. Fix this by returning the actual return
value of the read operation which is either 0 on success or an error
value.

Addresses-Coverity-ID: 1527254 ("Error handling issues")
Reported-by: coverity-bot <keescook+coverity-bot@chromium.org>
Fixes: 80a21da3 ("media: tc358746: add Toshiba TC358746 Parallel to CSI-2 bridge driver")
Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

drivers/media/i2c/tc358746.c

@@ -988,6 +988,7 @@ static int __maybe_unused
 tc358746_g_register(struct v4l2_subdev *sd, struct v4l2_dbg_register *reg)
 {
 	struct tc358746 *tc358746 = to_tc358746(sd);
+	int err;
 
 	/* 32-bit registers starting from CLW_DPHYCONTTX */
 	reg->size = reg->reg < CLW_DPHYCONTTX_REG ? 2 : 4;
@@ -995,12 +996,12 @@ tc358746_g_register(struct v4l2_subdev *sd, struct v4l2_dbg_register *reg)
 	if (!pm_runtime_get_if_in_use(sd->dev))
 		return 0;
 
-	tc358746_read(tc358746, reg->reg, (u32 *)&reg->val);
+	err = tc358746_read(tc358746, reg->reg, (u32 *)&reg->val);
 
 	pm_runtime_mark_last_busy(sd->dev);
 	pm_runtime_put_sync_autosuspend(sd->dev);
 
-	return 0;
+	return err;
 }
 
 static int __maybe_unused