efi: Fix several memory leaks of UEFI handles

Fix possible and absolute memory leaks of "handles"
returned by grub_efi_locate_handle() using grub_malloc().

Signed-off-by: Khalid Ali <khaliidcaliy@gmail.com>
Reviewed-by: Sudhakar Kuppusamy <sudhakar@linux.ibm.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

grub-core/video/efi_gop.c

@@ -94,7 +94,7 @@ check_protocol (void)
   gop_handle = 0;
 
   grub_dprintf ("video", "GOP: no usable mode\n");
-
+  grub_free (handles);
   return 0;
 }