sepolicy: add persist file access for hvdcp

hvdcp_opti daemon needs to store some parameters under vendor
persist (/mnt/vendor/persist/hvdcp_opti/*). Add the necessary
rule for it.

Also, move hvdcp.te from generic/vendor/common to qva/vendor/common.

Change-Id: I337b9c862d15c1080f7f7de7ba2fe26111d9f02b