efi_loader: correct function comment style

Replace @return and @param.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
diff --git a/lib/efi_selftest/efi_selftest_exitbootservices.c b/lib/efi_selftest/efi_selftest_exitbootservices.c
index 59ab154..f5e0d9d 100644
--- a/lib/efi_selftest/efi_selftest_exitbootservices.c
+++ b/lib/efi_selftest/efi_selftest_exitbootservices.c
@@ -63,7 +63,7 @@
  *
  * @handle:	handle of the loaded image
  * @systable:	system table
- * @return:	EFI_ST_SUCCESS for success
+ * Return:	EFI_ST_SUCCESS for success
  */
 static int setup(const efi_handle_t handle,
 		 const struct efi_system_table *systable)
@@ -101,7 +101,7 @@
  * Call ExitBootServices again and check that the notification function is
  * not called again.
  *
- * @return:	EFI_ST_SUCCESS for success
+ * Return:	EFI_ST_SUCCESS for success
  */
 static int execute(void)
 {