p54: replace MAC80211_LEDS with P54_LEDS in p54.h

I'm very sorry, as this change belongs to the other patch:
"[PATCH] p54: fix SoftLED compile dependencies".
however I must have somehow lost "git add" for that file.

Signed-off-by: Christian Lamparter <chunkeey@web.de>
Acked-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>