staging: brcm80211: restrict register access method for bcm47xx

The driver contained conditional code for resolving issue with
dma transaction reordering. This code was conditionalized using
__mips__ macro, but it actually is specific to bcm47xx chips.
This patch replaces it for the more speficic CONFIG_BCM47XX macro.

Tested on BCM63281.

Reviewed-by: Henry Ptasinski <henryp@broadcom.com>
Reviewed-by: Roland Vossen <rvossen@broadcom.com>
Tested-by: Jonas Gorski <jonas.gorski@gmail.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/brcm80211/brcmsmac/phy/phy_cmn.c

@@ -380,7 +380,7 @@ void write_phy_reg(struct brcms_phy *pi, u16 addr, u16 val)
 
 	regs = pi->regs;
 
-#ifdef __mips__
+#ifdef CONFIG_BCM47XX
 	W_REG_FLUSH(&regs->phyregaddr, addr);
 	W_REG(&regs->phyregdata, val);
 	if (addr == 0x72)

drivers/staging/brcm80211/brcmsmac/types.h

@@ -362,7 +362,7 @@ do {						\
 		} \
 	} while (0)
 
-#ifdef __mips__
+#ifdef CONFIG_BCM47XX
 /*
  * bcm4716 (which includes 4717 & 4718), plus 4706 on PCIe can reorder
  * transactions. As a fix, a read after write is performed on certain places
@@ -371,7 +371,7 @@ do {						\
 #define W_REG_FLUSH(r, v)	({ W_REG((r), (v)); (void)R_REG(r); })
 #else
 #define W_REG_FLUSH(r, v)	W_REG((r), (v))
-#endif				/* __mips__ */
+#endif				/* CONFIG_BCM47XX */
 
 #define AND_REG(r, v)	W_REG((r), R_REG(r) & (v))
 #define OR_REG(r, v)	W_REG((r), R_REG(r) | (v))