Add permission for VFIO device binding

vfio_handler will bind platform devices to VFIO driver, and then
return a file descriptor containing DTBO. This change adds
permissions needed for that.

Bug: 278008182
Test: adb shell /apex/com.android.virt/bin/vm run-microdroid \
      --devices /sys/bus/platform/devices/16d00000.eh --protected
Change-Id: Ie947adff00d138426d4703cbb8e7a8cd429c2272
diff --git a/private/file_contexts b/private/file_contexts
index 0bae96e..c2a6269 100644
--- a/private/file_contexts
+++ b/private/file_contexts
@@ -190,6 +190,7 @@
 /dev/urandom		u:object_r:random_device:s0
 /dev/usb_accessory	u:object_r:usbaccessory_device:s0
 /dev/v4l-touch[0-9]*	u:object_r:input_device:s0
+/dev/vfio(/.*)?		u:object_r:vfio_device:s0
 /dev/vhost-vsock	u:object_r:kvm_device:s0
 /dev/video[0-9]*	u:object_r:video_device:s0
 /dev/vndbinder		u:object_r:vndbinder_device:s0