PNP: Convert pnp_lock into a mutex

pnp_lock is a spinlock, but it is only acquired from process context,
so it may be a mutex just fine.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --cc drivers/pnp/base.h
Simple merge

diff --cc drivers/pnp/card.c
Simple merge

diff --cc drivers/pnp/core.c
Simple merge

diff --cc drivers/pnp/driver.c
Simple merge