staging: brcm80211: SPARC build error fix

Due to missing memset function declaration.
Reviewed-by: NRoland Vossen <rvossen@broadcom.com>
Signed-off-by: NArend van Spriel <arend@broadcom.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/staging/brcm80211/brcmsmac/otp.c

@@ -16,6 +16,7 @@
 
 #include <linux/io.h>
 #include <linux/errno.h>
+#include <linux/string.h>
 
 #include <brcm_hw_ids.h>
 #include <chipcommon.h>