Revert "Allowe system_app to access UEvent"

This reverts commit 615c724fee.

This doesn't compile, and actually I intented to target platform_app,
which already have this permission.

sepolicy/hardware_overlay.te

@@ -1,2 +1 @@
 allow priv_app overlay_service:service_manager find;
-allow system_app self:netlink_kobject_uevent_socket create_socket_perms_no_ioctl;