omni: Fix vold sepolicy denials

like and all others

10-03 23:34:22.422   552   552 W binder:552_1: type=1400 audit(0.0:211): avc: denied { execute } for name="mkfs.exfat" dev="dm-0" ino=1463 scontext=u:r:vold:s0 tcontext=u:object_r:mkfs_exec:s0 tclass=file permissive=0

Change-Id: I0503f3ebce228dfaab14c0c2e49273a4f851ae0a
diff --git a/sepolicy/private/vold.te b/sepolicy/private/vold.te
index 52b61e5..f6e0d69 100644
--- a/sepolicy/private/vold.te
+++ b/sepolicy/private/vold.te
@@ -1,4 +1,4 @@
 #============= vold ==============
 allow vold block_device:blk_file { getattr };
 allow vold fsck_exec:lnk_file read;
-
+allow vold mkfs_exec:file rx_file_perms;