sepolicy: Allow mediaserver to get vendor_display_prop

[1] - 01-01 16:27:45.302 W/binder:1342_3(1342): type=1400 audit(0.0:34477): avc:  denied  { read } for  name="u:object_r:vendor_display_prop:s0" dev="tmpfs" ino=18646 scontext=u:r:mediaserver:s0 tcontext=u:object_r:vendor_display_prop:s0 tclass=file permissive=0
[2] - 01-01 16:27:39.783 W/libc    (1342): Access denied finding property "vendor.display.enable_optimal_refresh_rate"

Change-Id: I2f97ba234e2c0bf658f4e91c936e3ef38ce5a41f
Signed-off-by: chrisl7 <wandersonrodriguesf1@gmail.com>

sepolicy/generic/vendor/mediaserver.te

@@ -0,0 +1 @@
+get_prop(mediaserver, vendor_display_prop)