Staging: rt2870: Allow building on ARM

Signed-off-by: NHoward Chu <hyc@symas.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/staging/rt2870/Kconfig

 config RT2870
 	tristate "Ralink 2870/3070 wireless support"
-	depends on USB && X86 && WLAN
+	depends on USB && (X86 || ARM) && WLAN
 	select WIRELESS_EXT
 	select WEXT_PRIV
 	select CRC_CCITT