mmd: allow mmd.zram.enabled shared between system_server

system_server reads mmd.zram.enabled system property to switch zram
management system between mmd and the old one.

Bug: 393481329
Test: manual

Change-Id: I0222c84152fb2538fbd04fb3e90a829970116f2e
diff --git a/private/property_contexts b/private/property_contexts
index b0c1d23..44b6d33 100644
--- a/private/property_contexts
+++ b/private/property_contexts
@@ -1818,4 +1818,5 @@
 
 # Properties for mmd
 mmd. u:object_r:mmd_prop:s0
+mmd.zram.enabled u:object_r:mmd_shared_prop:s0 exact bool
 mmd.enabled_aconfig u:object_r:mmd_status_prop:s0 exact bool