wireless: fix warning introduced by "mac80211: QoS related cleanups"

net/mac80211/wme.c: In function ‘wme_qdiscop_enqueue’:
net/mac80211/wme.c:219: warning: comparison is always false due to limited range of data type

drivers/net/wireless/p54/p54common.c: In function ‘p54_conf_tx’:
drivers/net/wireless/p54/p54common.c:947: warning: comparison is always false due to limited range of data type

Signed-off-by: John W. Linville <linville@tuxdriver.com>