rt2x00: Comment spellchecking

Fix a bunch of spelling errors in the rt2x00 drivers

Signed-off-by: Luis Correia <luis.f.correia@gmail.com>
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 5bc46fe..b01edca 100644
--- a/drivers/net/wireless/rt2x00/rt2500usb.h
+++ b/drivers/net/wireless/rt2x00/rt2500usb.h
@@ -831,7 +831,7 @@
 #define RXD_W3_EIV			FIELD32(0xffffffff)
 
 /*
- * Macro's for converting txpower from EEPROM to mac80211 value
+ * Macros for converting txpower from EEPROM to mac80211 value
  * and from mac80211 value to register value.
  */
 #define MIN_TXPOWER	0