net: stmmac: dwmac-anarion: Use annotation __iomem for register base

Use __iomem annotation the register base: the ctl_block field of struct
anarion_gmac. I believe this is the normal practice for such variables.

By doing so some casting is avoided.
And sparse no longer reports:

 .../dwmac-anarion.c:29:23: warning: incorrect type in argument 1 (different address spaces)
 .../dwmac-anarion.c:29:23:    expected void const volatile [noderef] __iomem *addr
 .../dwmac-anarion.c:29:23:    got void *
 .../dwmac-anarion.c:34:22: warning: incorrect type in argument 2 (different address spaces)
 .../dwmac-anarion.c:34:22:    expected void volatile [noderef] __iomem *addr
 .../dwmac-anarion.c:34:22:    got void *

No functional change intended.
Compile tested only.
Signed-off-by: Simon Horman <horms@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/stmicro/stmmac/dwmac-anarion.c

@@ -20,18 +20,18 @@
 #define  GMAC_CONFIG_INTF_RGMII		(0x1 << 0)
 
 struct anarion_gmac {
-	uintptr_t ctl_block;
+	void __iomem *ctl_block;
 	uint32_t phy_intf_sel;
 };
 
 static uint32_t gmac_read_reg(struct anarion_gmac *gmac, uint8_t reg)
 {
-	return readl((void *)(gmac->ctl_block + reg));
+	return readl(gmac->ctl_block + reg);
 };
 
 static void gmac_write_reg(struct anarion_gmac *gmac, uint8_t reg, uint32_t val)
 {
-	writel(val, (void *)(gmac->ctl_block + reg));
+	writel(val, gmac->ctl_block + reg);
 }
 
 static int anarion_gmac_init(struct platform_device *pdev, void *priv)
@@ -77,7 +77,7 @@ static struct anarion_gmac *anarion_config_dt(struct platform_device *pdev)
 	if (!gmac)
 		return ERR_PTR(-ENOMEM);
 
-	gmac->ctl_block = (uintptr_t)ctl_block;
+	gmac->ctl_block = ctl_block;
 
 	err = of_get_phy_mode(pdev->dev.of_node, &phy_mode);
 	if (err)