efi_loader: don't increment part twice per loop

Correct a mistake in the part number handling of commit
16a73b249d and only increment part once
per loop.

Signed-off-by: Jonathan Gray <jsg@jsg.id.au>
Tested-by: Peter Robinson <pbrobinson@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>

lib/efi_loader/efi_disk.c

@@ -360,7 +360,6 @@ int efi_disk_register(void)
 					continue;
 				efi_disk_add_dev(devname, if_typename, desc,
 						 i, 0, part);
-				part++;
 			}
 
 			/* ... and add block device: */