Revert "fstab: mount modem partition with firmware_file context"

This reverts commit 3a50149bbd91a288ed3c6fe6a8026c4c32caa934.

Change-Id: Ifdf03ec08f9e9f9f095b598b0c2399422542c505
Merge "Revert "fstab: mount modem partition with firmware_file context"" into lollipop