[MIPS] Lasat: Convert pvc_sem semaphore to mutex

I also changed the name to pvc_mutex, and moved the define to the file
it's used in which allows it to be static.

Signed-off-by: Daniel Walker <dwalker@mvista.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
3 files changed