staging: brcm80211: add braces to SI_INFO macro definition

The additional braces allow the casted parameter to be indirected
immediately. Here is an example to clarify:
	x = SI_INFO(y);    => z = SI_INFO(y)->field_a;
	z = x->field_a;
Signed-off-by: NArend van Spriel <arend@broadcom.com>
Reviewed-by: NRoland Vossen <rvossen@broadcom.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/staging/brcm80211/brcmsmac/aiutils.h

@@ -271,7 +271,7 @@
 #define	CST4330_CBUCK_POWER_OK		0x00004000
 #define	CST4330_BB_PLL_LOCKED		0x00008000
 
-#define	SI_INFO(sih)	(si_info_t *)sih
+#define	SI_INFO(sih)	((si_info_t *)sih)
 
 #define	GOODCOREADDR(x, b) \
 	(((x) >= (b)) && ((x) < ((b) + SI_MAXCORES * SI_CORE_SIZE)) && \