dragonboard: sepolicy: Add sepolicy rules to fix problems seen adb remount overlays

When using adb remount/adb sync, I noticed some new sepolicy
failures that prevented some things from working.

For instance, if I did adb remount right after flashing a
device, on the next bootup I found that wifi would fail to work.
This was due to sepolicy failures caused by the file accesses
being on the overlayfs.

Similarly, when testing a new version of mesa via adb sync, I
found surfaceflinger would fail to start, again due to new
sepolicy failures

These sepolicy changes were suggested by audit2allow to fix
the problems, and indeed I now have display and wifi working
after adb remount/sync updates.

Signed-off-by: John Stultz <jstultz@google.com>
Change-Id: Ifd819cf34939d1e61b67d8b08c67ec9a2fadd110
diff --git a/sepolicy/system_server.te b/sepolicy/system_server.te
index 80957cc..e801436 100644
--- a/sepolicy/system_server.te
+++ b/sepolicy/system_server.te
@@ -1 +1,3 @@
 gpu_access(system_server)
+allow system_server wifi_hal_prop:file {open read getattr map};
+allow system_server vendor_file:dir read;