add logd. as logd_prop

We already have ro.logd. and persist.logd. as logd_prop, but not
logd. so this change adds it.  New properties should be read-write by
default so logd. should be preferred to ro.logd.

Test: set logd.buffer_type appropriately.
Change-Id: I51ed19f0093a0302709116944153f37067814d08
diff --git a/private/property_contexts b/private/property_contexts
index b89d4e4..14ec03d 100644
--- a/private/property_contexts
+++ b/private/property_contexts
@@ -54,6 +54,7 @@
 persist.bluetooth.      u:object_r:bluetooth_prop:s0
 persist.nfc_cfg.        u:object_r:nfc_prop:s0
 persist.debug.          u:object_r:persist_debug_prop:s0
+logd.                   u:object_r:logd_prop:s0
 persist.logd.           u:object_r:logd_prop:s0
 ro.logd.                u:object_r:logd_prop:s0
 persist.logd.security   u:object_r:device_logging_prop:s0