net: ibm: emac: Use __iomem annotation for emac_[xg]aht_base

dev->emacp contains an __iomem pointer and values derived
from it are used as __iomem pointers. So use this annotation
in the return type for helpers that derive pointers from dev->emacp.

Flagged by Sparse as:

.../core.c:444:36: warning: incorrect type in argument 1 (different address spaces)
.../core.c:444:36:    expected unsigned int volatile [noderef] [usertype] __iomem *addr
.../core.c:444:36:    got unsigned int [usertype] *
.../core.c: note: in included file:
.../core.h:416:25: warning: cast removes address space '__iomem' of expression

Compile tested only.
No functional change intended.
Signed-off-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20240906-emac-iomem-v1-1-207cc4f3fed0@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/ibm/emac/core.c

@@ -418,8 +418,8 @@ static int emac_reset(struct emac_instance *dev)
 
 static void emac_hash_mc(struct emac_instance *dev)
 {
+	u32 __iomem *gaht_base = emac_gaht_base(dev);
 	const int regs = EMAC_XAHT_REGS(dev);
-	u32 *gaht_base = emac_gaht_base(dev);
 	u32 gaht_temp[EMAC_XAHT_MAX_REGS];
 	struct netdev_hw_addr *ha;
 	int i;

drivers/net/ethernet/ibm/emac/core.h

@@ -400,7 +400,7 @@ static inline int emac_has_feature(struct emac_instance *dev,
 	((u32)(1 << (EMAC_XAHT_WIDTH(dev) - 1)) >>	\
 	 ((slot) & (u32)(EMAC_XAHT_WIDTH(dev) - 1)))
 
-static inline u32 *emac_xaht_base(struct emac_instance *dev)
+static inline u32 __iomem *emac_xaht_base(struct emac_instance *dev)
 {
 	struct emac_regs __iomem *p = dev->emacp;
 	int offset;
@@ -413,10 +413,10 @@ static inline u32 *emac_xaht_base(struct emac_instance *dev)
 	else
 		offset = offsetof(struct emac_regs, u0.emac4.iaht1);
 
-	return (u32 *)((ptrdiff_t)p + offset);
+	return (u32 __iomem *)((__force ptrdiff_t)p + offset);
 }
 
-static inline u32 *emac_gaht_base(struct emac_instance *dev)
+static inline u32 __iomem *emac_gaht_base(struct emac_instance *dev)
 {
 	/* GAHT registers always come after an identical number of
 	 * IAHT registers.