pixel-sepolicy: init_dpm.sh to read/write on custom_ab_block_device

DPM images can have "custom_ab_block_device" label. Thus, we should
allow init_dpm.sh to read/write on custom_ab_block_device.

Bug: 283725554

Change-Id: I37e680373f2194e5a858eb32e810461b1c0091dd
Signed-off-by: Bryan Bong Gyoune Kim <bgkim@google.com>
diff --git a/debugpolicy/init_dpm.te b/debugpolicy/init_dpm.te
index 3a4f936..8938eef 100644
--- a/debugpolicy/init_dpm.te
+++ b/debugpolicy/init_dpm.te
@@ -8,4 +8,5 @@
 allow init_dpm sysfs_dpm:file r_file_perms;
 allow init_dpm block_device:dir search;
 allow init_dpm dpm_block_device:blk_file rw_file_perms;
+allow init_dpm custom_ab_block_device:blk_file rw_file_perms;
 ')