netdev: ehea: semaphore to mutex

Converted the dlpar_mem_lock.  With a bit of cleanup, I converted to
DEFINE_MUTEX() instead of a runtime init.  I also made the lock static.

Signed-off-by: Daniel Walker <dwalker@mvista.com>
Cc: Christoph Raisch <raisch@de.ibm.com>
Acked-by: Jan-Bernd Themann <themann@de.ibm.com>
Cc: Thomas Klein <tklein@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>