tee: shm: inline tee_shm_get_id()

Now, when struct tee_shm is defined in public header,
we can inline small getter functions like this one.

Signed-off-by: Volodymyr Babchuk <vlad.babchuk@gmail.com>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>

include/linux/tee_drv.h

@@ -438,7 +438,10 @@ static inline size_t tee_shm_get_page_offset(struct tee_shm *shm)
  * @shm:	Shared memory handle
  * @returns id
  */
-int tee_shm_get_id(struct tee_shm *shm);
+static inline int tee_shm_get_id(struct tee_shm *shm)
+{
+	return shm->id;
+}
 
 /**
  * tee_shm_get_from_id() - Find shared memory object and increase reference