drm/i915/pxp: Create the arbitrary session after boot

Create the arbitrary session, with the fixed session id 0xf, after system boot, for the case that application allocates the protected buffer without establishing any protection session. Because the hardware requires at least one alive session for protected buffer creation. This arbitrary session will need to be re-created after teardown or power event because hardware encryption key won't be valid after such cases. The session ID is exposed as part of the uapi so it can be used as part of userspace commands. v2: use gt->uncore->rpm (Chris) v3: s/arb_is_in_play/arb_is_valid (Chris), move set-up to the new init_hw function v4: move interface defs to separate header, set arb_is valid to false on fini (Rodrigo) v5: handle async component binding

HSHuang, Sean Z committed 5 years ago