gsi: sepolicy: Allow network_stack to access fs_bpf

Commit e00315 [packages/modules/Connectivity] introduced
isUidNetworkingBlocked which requires accessing fs_bpf_netd_private.
This is not present on devices with R vendor.

Let's simply fix it by allowing all bpf access for now.

sepolicy/private/network_stack.te

@@ -0,0 +1,4 @@
+# R vendor devices may not have fs_bpf_netd_private etc.
+# Allow network stack to do whatever with fs_bpf
+allow network_stack fs_bpf:dir search;
+allow network_stack fs_bpf:file { getattr read write };