init.te: allow create sdcard link in /mnt

to avoid avc like following:
avc:  denied  { create } for  pid=1 comm="init" name="sdcard" scontext=u:r:init:s0 tcontext=u:object_r:tmpfs:s0 tclass=lnk_file permissive=1

Change-Id: I8d8adbf2819f5b6e09a1dae95816c731e495cbac
Signed-off-by: Yongqin Liu <yongqin.liu@linaro.org>
diff --git a/sepolicy/init.te b/sepolicy/init.te
index f14792a..16d3a3e 100644
--- a/sepolicy/init.te
+++ b/sepolicy/init.te
@@ -2,3 +2,5 @@
 allow init configfs:dir create_dir_perms;
 allow init configfs:file write;
 allow init configfs:lnk_file { create unlink };
+# for symlink /sdcard /mnt/sdcard
+allow init tmpfs:lnk_file create;