ACPI / EC: Cleanup the member name for spinlock/mutex in struct

Current member names for mutex/spinlock are a little confusing.

Change the
{
	struct mutex lock;
	spinlock_t curr_lock;
}
to
{
	struct mutex mutex;
	spinlock_t lock;
}

So that the code is cleaner and easier to read.

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