drm/i915/uc: Fetch GuC/HuC firmwares from guc/huc specific init

We're fetching GuC/HuC firmwares directly from uc level during
init_early stage but this breaks guc/huc struct isolation and
also strict SW-only initialization rule for init_early. Move fw
fetching to init phase and do it separately per guc/huc struct.

v2: don't forget to move wopcm_init - Michele
v3: fetch in init_misc phase - Michal

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Michel Thierry <michel.thierry@intel.com>
Reviewed-by: Michel Thierry <michel.thierry@intel.com> #2
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20180628141522.62788-2-michal.wajdeczko@intel.com