sepolicy: mount firmware partitions with firmware_file context

* we don't need to give ueventd access across the entire vfat context

Change-Id: Idf1e24b7b90fd439d1d3ee2cd839c43078f026c7
m8: update blob list and extract-files

Change-Id: I869a4a2690fb545bfb47544c5332f0c6655fa13d