wireless: brcmsmac: fix old-style declaration

Modern C standards expect the 'static' keyword to come first in a
declaration, and we get a warning for this with "make W=1":

drivers/net/wireless/broadcom/brcm80211/brcmsmac/main.c:3353:1: error: 'static' is not at beginning of declaration [-Werror=old-style-declaration]

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>