drm/i915/uc: Move uc firmware layout definitions to dedicated file

Generic uc firmware layout definitions are unlikely to change and
are separate to other GuC specific definitions.

v2: reordered

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190725141308.24660-3-michal.wajdeczko@intel.com