Revert "set CPU_VARIANT to contex-a8"

This reverts commit e07606ffe9c3b109e14c5eeee182920539c65305.
Revert "set persist.sys.purgeable_assets"

This reverts commit ce0a94a7cabe8e5fb685cbd60b9cdef488992b57.
Add default root access mode
update unified fstab for recovery
usb: add missing MTP/PTP triggers