wl1251: use wl1251 prefix everywhere

Last we can change all code prefixes from wl12xx/WL12XX to
wl1251/WL1251.

Signed-off-by: Kalle Valo <kalle.valo@nokia.com>
Reviewed-by: Vidhya Govindan <vidhya.govindan@nokia.com>
Reviewed-by: Luciano Coelho <luciano.coelho@nokia.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
26 files changed