staging: brcm80211: fix compile error on non-x86 archs since 3.0 kernel

Since the arrival of kernel version 3.0 in the staging tree it
turns out compile error occurs for sparc64, powerpc, and arm
platforms. This patch fixes that issue.

Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Reviewed-by: Henry Ptasinski <henryp@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>