brcmfmac: include linux/vmalloc.h from usb.c

This avoids build failures on some architectures...

Signed-off-by: John W. Linville <linville@tuxdriver.com>
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Acked-by: Arend van Spriel <arend@broadcom.com>

drivers/net/wireless/brcm80211/brcmfmac/usb.c

@@ -18,6 +18,7 @@
 #include <linux/module.h>
 #include <linux/firmware.h>
 #include <linux/usb.h>
+#include <linux/vmalloc.h>
 
 #include <brcmu_utils.h>
 #include <brcmu_wifi.h>