net: bgmac: Correctly annotate register space

All the members: base, idm_base and nicpm_base should be annotated with
__iomem since they are pointers to register space. This fixes a bunch of
sparse reported warnings.

Fixes: f6a95a24957a ("net: ethernet: bgmac: Add platform device support")
Fixes: dd5c5d037f5e ("net: ethernet: bgmac: add NS2 support")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bgmac.h

@@ -479,9 +479,9 @@ struct bgmac_rx_header {
 struct bgmac {
 	union {
 		struct {
-			void *base;
-			void *idm_base;
-			void *nicpm_base;
+			void __iomem *base;
+			void __iomem *idm_base;
+			void __iomem *nicpm_base;
 		} plat;
 		struct {
 			struct bcma_device *core;