rt2x00: Simplify rt2x00_check_rev

rt2x00_check_rev() was too specific for rt2500usb and rt73usb,
by adding the mask argument (instead of hardcoding it into
the function itself) we can use the function in rt2800usb as
well.

v2: Fix revision mask for rt2800usb

Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/rt2x00/rt2500usb.c b/drivers/net/wireless/rt2x00/rt2500usb.c
index 08e8833..1debb88 100644
--- a/drivers/net/wireless/rt2x00/rt2500usb.c
+++ b/drivers/net/wireless/rt2x00/rt2500usb.c
@@ -1559,7 +1559,7 @@
 	rt2500usb_register_read(rt2x00dev, MAC_CSR0, &reg);
 	rt2x00_set_chip(rt2x00dev, RT2570, value, reg);
 
-	if (!rt2x00_check_rev(&rt2x00dev->chip, 0)) {
+	if (!rt2x00_check_rev(&rt2x00dev->chip, 0x000ffff0, 0)) {
 		ERROR(rt2x00dev, "Invalid RT chipset detected.\n");
 		return -ENODEV;
 	}