drivers/edac: fix edac_device semaphore to mutex

A previous patch changed the edac_mc src file from semaphore usage to mutex
This patch changes the edac_device src file as well, from semaphore use to
mutex operation.

Use a mutex primitive for mutex operations, as it does not require a
semaphore

Cc: Alan Cox alan@lxorguk.ukuu.org.uk
Signed-off-by: Doug Thompson <dougthompson@xmission.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>