power: device_pm: Use spin lock instead of semaphore

Device pm runtime was using semaphore to protect critical section but
enable / disable functions were waiting on the semaphore. So, just
replace it with a spin lock.

Signed-off-by: Flavio Ceolin <flavio.ceolin@intel.com>

include/pm/device.h

@@ -87,7 +87,7 @@ struct pm_device {
 	/** Pointer to the device */
 	const struct device *dev;
 	/** Lock to synchronize the get/put operations */
-	struct k_sem lock;
+	struct k_spinlock lock;
 	/* Following are packed fields protected by #lock. */
 	/** Device pm enable flag */
 	bool enable : 1;