drm/i915/uc: Place uC firmware in upper range of GGTT

drm/i915/uc: Place uC firmware in upper range of GGTT

Currently we pin the GuC or HuC firmware image just before uploading.
Perma-pin during uC initialization instead and use the range reserved at
the top of the address space.

Moving the firmware resulted in needing to:
- use an additional pinning for the rsa signature which will be used
  during HuC auth as addresses above GUC_GGTT_TOP do not map through GTT.

v2: Remove call to set to gtt domain
    Do not restore fw gtt mapping unconditionally
    Separate out pin/unpin functions and drop usage of pin/unpin
    Use uc_fw init/fini functions to bind/unbind fw object

v3: Bind is only needed during xfer (Chris)
    Remove attempts to bind outside of xfer (Chris)
    Mark fw bind/unbind static

Signed-off-by: Fernando Pacheco <fernando.pacheco@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190419230015.18121-4-fernando.pacheco@intel.com