Allow sdcardd to remount sdcardfs

Sdcardfs now supports bind mounts and remounts
instead of needing several separate mounts

bug: 30954918
Test: Enable Sdcardfs, verify mounts
Change-Id: Id94713752a08ceeb6aea7d3c29a29d3293a9b0c8

public/sdcardd.te

@@ -4,6 +4,7 @@ type sdcardd_exec, exec_type, file_type;
 allow sdcardd cgroup:dir create_dir_perms;
 allow sdcardd fuse_device:chr_file rw_file_perms;
 allow sdcardd rootfs:dir mounton;  # TODO: deprecated in M
+allow sdcardd sdcardfs:filesystem remount;
 allow sdcardd tmpfs:dir r_dir_perms;
 allow sdcardd mnt_media_rw_file:dir r_dir_perms;
 allow sdcardd storage_file:dir search;