drm/i915/guc: Consolidate firmware major-minor to one place

Currently to change the firmware one has to update the exported
module firmware string and the major-minor versions used for
verification after load. Consolidate that to a single place
defining correct major and minor versions per platform.

v2: Rebased for KBL.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Dave Gordon <david.s.gordon@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Peter Antoine <peter.antoine@intel.com>
Cc: Michel Thierry <michel.thierry@intel.com>
Reviewed-by: Dave Gordon <david.s.gordon@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470842206-35685-1-git-send-email-tvrtko.ursulin@linux.intel.com