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/term/efi/serial.c

@@ -169,13 +169,13 @@ grub_efiserial_init (void)
 
       port = grub_zalloc (sizeof (*port));
       if (!port)
-	return;
+	break;
 
       port->name = grub_malloc (sizeof ("efiXXXXXXXXXXXXXXXXXXXX"));
       if (!port->name)
 	{
 	  grub_free (port);
-	  return;
+	  break;
 	}
       grub_snprintf (port->name, sizeof ("efiXXXXXXXXXXXXXXXXXXXX"),
 		     "efi%d", num_serial++);