[ALPS03841839] Add policy for using nvram function

[Detail]
The P version change nvdata path to /mnt/vendor/nvdata.
If want to open fstab when using nvram function,
it needs search policy.

[Solution]
allow xxx mnt_vendor_file:dir search

MTK-Commit-Id: a34d6ff7cf3b1545014a45f5052f7dbddf93808a

Change-Id: I2730d51963d3859008b4a53f06329ef0a23eb8f4
CR-Id: ALPS03841839
Feature: NVRAM Partition