brcmsmac: initialize morepending in brcms_b_recv()

drivers/net/wireless/brcm80211/brcmsmac/main.c: In function ‘brcms_b_recv’:
drivers/net/wireless/brcm80211/brcmsmac/main.c:7636: warning: ‘morepending’ may be used uninitialized in this function

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>