tee: shm: add accessors for buffer size and page offset

These two function will be needed for shared memory registration in OP-TEE
Signed-off-by: Volodymyr Babchuk <vlad.babchuk@gmail.com>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>

include/linux/tee_drv.h

@@ -393,6 +393,26 @@ void *tee_shm_get_va(struct tee_shm *shm, size_t offs);
  */
 int tee_shm_get_pa(struct tee_shm *shm, size_t offs, phys_addr_t *pa);
 
+/**
+ * tee_shm_get_size() - Get size of shared memory buffer
+ * @shm:	Shared memory handle
+ * @returns size of shared memory
+ */
+static inline size_t tee_shm_get_size(struct tee_shm *shm)
+{
+	return shm->size;
+}
+
+/**
+ * tee_shm_get_page_offset() - Get shared buffer offset from page start
+ * @shm:	Shared memory handle
+ * @returns page offset of shared buffer
+ */
+static inline size_t tee_shm_get_page_offset(struct tee_shm *shm)
+{
+	return shm->offset;
+}
+
 /**
  * tee_shm_get_id() - Get id of a shared memory object
  * @shm:	Shared memory handle