timeservice_app: Fix denial to vendor_mpctl_prop

Add policy to fix denial to vendor_mpctl_prop:

avc: denied { read } for pid=4819 comm="omm.timeservice"
name="u:object_r:vendor_mpctl_prop:s0" dev="tmpfs" ino=15557
scontext=u:r:timeservice_app:s0:c109,c256,c512,c768
tcontext=u:object_r:vendor_mpctl_prop:s0 tclass=file permissive=0

CRs-Fixed: 2280780
Change-Id: I14ebc8d5b269eaf282b2fe7ad649d836502359e7