rt2x00: Minor optimization for devices with RTS/CTS offload

Only devices that don't have RTS/CTS offload need to check for
IEEE80211_TX_RC_USE_RTS_CTS and IEEE80211_TX_RC_USE_CTS_PROTECT.

By swapping both conditions we keep the same number of needed conditionals
for devices without RTS/CTS offload but save one conditional on devices
with RTS/CTS offload.

Signed-off-by: Helmut Schaa <helmut.schaa@googlemail.com>
Acked-by: Gertjan van Wingerde <gwingerde@gmail.com>
Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>