Make persist.sys.locale public-readable.

Addresses this denial:
avc: denied { read } for comm="rild" name="u:object_r:system_prop:s0"
dev="tmpfs" ino=15811 scontext=u:r:rild:s0 tcontext=u:object_r:system_prop:s0
tclass=file permissive=0

Fixes: 77960261
Test: m selinux_policy
Change-Id: I341675a4cfc0acbb7ea98e2ed4bdb7f69afe09f7