rt2x00: Implement HW encryption (rt2500usb)

rt2500usb supports hardware encryption.
rt2500usb supports up to 4 shared and pairwise keys.

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.h b/drivers/net/wireless/rt2x00/rt2500usb.h
index dbb5d689..4347dfd 100644
--- a/drivers/net/wireless/rt2x00/rt2500usb.h
+++ b/drivers/net/wireless/rt2x00/rt2500usb.h
@@ -447,6 +447,9 @@
 #define SEC_CSR30			0x04bc
 #define SEC_CSR31			0x04be
 
+#define KEY_ENTRY(__idx) \
+	( SEC_CSR0 + ((__idx) * 16) )
+
 /*
  * PHY control registers.
  */