drm/i915/uc: Don't fetch HuC fw if GuC fw fetch already failed

When we failed to fetch GuC firmware there is no point in fetching
HuC firmware as we will not be able to use it without working GuC.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
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/20190807170034.8440-4-michal.wajdeczko@intel.com