Ensure vold is a client of hal_bootctl only in Treble mode.

This fixes a build breakage.

Test: Build policy.
Change-Id: Id5209a2bd6446ac6dd744b7426f540bc1a8641ed

public/vold.te

@@ -165,7 +165,7 @@ hal_client_domain(vold, hal_keymaster)
 hal_client_domain(vold, hal_health_storage)
 
 # talk to bootloader HAL
-hal_client_domain(vold, hal_bootctl)
+full_treble_only(`hal_client_domain(vold, hal_bootctl)')
 
 # Access userdata block device.
 allow vold userdata_block_device:blk_file rw_file_perms;