sepolicy: restrict hal_graphics_allocator sysfs access

Grant access to sysfs_mdss_mdp_caps only instead of the entire
sysfs.

Bug: 36373038
Test: manual
Change-Id: Idd39ebf2c4cbf2e45f8cac44fcc69c03bb523ad1
diff --git a/sepolicy/hal_graphics_allocator.te b/sepolicy/hal_graphics_allocator.te
index fa7fce3..84b36a3 100644
--- a/sepolicy/hal_graphics_allocator.te
+++ b/sepolicy/hal_graphics_allocator.te
@@ -1 +1,2 @@
-r_dir_file(hal_graphics_allocator, sysfs_type)
+# needed for querySDEInfo
+allow hal_graphics_allocator sysfs_mdss_mdp_caps:file r_file_perms;