sa1100fb: convert ctrlr_sem in a mutex

The semaphore ctrlr_sem is used as a mutex.  Convert it to the mutex API

Signed-off-by: Matthias Kaehlcke <matthias@kaehlcke.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>