Fix permissions for vold.post_fs_data_done

The system property "vold.post_fs_data_done" is used by init and vold to
communicate with each other in order to set up FDE on devices that use
FDE.  It needs to be gettable and settable by vold, and settable by init
and vendor_init.  This was the case in Android 11 and earlier; however,
the change
https://android-review.googlesource.com/c/platform/system/sepolicy/+/1277447
("Rename exported and exported2 vold prop") broke this by giving this
property the type "vold_config_prop", which made it no longer settable
by vold.

Since none of the existing property types appear to be appropriate for
this particular property, define a new type "vold_post_fs_data_prop" and
grant the needed domains permission to get/set it.

This is one of a set of changes that is needed to get FDE working again
so that devices that launched with FDE can be upgraded to Android 12.

Bug: 186165644
Test: Tested FDE on Cuttlefish
Change-Id: I2fd8af0091f8b921ec37381ad3b85a156d074566
diff --git a/private/compat/30.0/30.0.cil b/private/compat/30.0/30.0.cil
index c158a30..c7a84ff 100644
--- a/private/compat/30.0/30.0.cil
+++ b/private/compat/30.0/30.0.cil
@@ -1378,7 +1378,10 @@
     dalvik_runtime_prop
     surfaceflinger_color_prop
     zram_control_prop))
-(typeattributeset exported2_vold_prop_30_0 (exported2_vold_prop vold_config_prop))
+(typeattributeset exported2_vold_prop_30_0
+  ( exported2_vold_prop
+    vold_config_prop
+    vold_post_fs_data_prop))
 (typeattributeset exported3_default_prop_30_0
   ( exported3_default_prop
     camera_calibration_prop