Adds GPU sepolicy to support devices with DRM gralloc/rendering

... such as Cuttlefish (Cloud Android virtual device) which has a
DRM virtio-gpu based gralloc and (sometimes) DRM virtio-gpu based
rendering (when forwarding rendering commands to the host machine
with Mesa3D in the guest and virglrenderer on the host).

After this change is submitted, changes such as aosp/1997572 can
be submitted to removed sepolicy that is currently duplicated
across device/google/cuttlefish and device/linaro/dragonboard as
well.

Adds a sysfs_gpu type (existing replicated sysfs_gpu definitions
across several devices are removed in the attached topic). The
uses of `sysfs_gpu:file` comes from Mesa using libdrm's
`drmGetDevices2()` which calls into `drmParsePciDeviceInfo()` to
get vendor id, device id, version etc.

Ignore-AOSP-First: must be submitted in internal as a topic first to
                   avoid having duplicate definitions of sysfs_gpu
                   in projects that are only available in internal

Bug: b/161819018
Test: launch_cvd
Test: launch_cvd --gpu_mode=gfxstream
Change-Id: I4f7d4b0fb90bfeef72f94396ff0c5fe44d53510c
Merged-In: I4f7d4b0fb90bfeef72f94396ff0c5fe44d53510c
diff --git a/private/app.te b/private/app.te
index 02acd6e..b7da601 100644
--- a/private/app.te
+++ b/private/app.te
@@ -354,6 +354,9 @@
 # Grant GPU access to all processes started by Zygote.
 # They need that to render the standard UI.
 allow { appdomain -isolated_app } gpu_device:chr_file rw_file_perms;
+allow { appdomain -isolated_app } gpu_device:dir r_dir_perms;
+allow { appdomain -isolated_app } sysfs_gpu:file r_file_perms;
+
 
 # Use the Binder.
 binder_use(appdomain)