drm/i915/guc: enable GuC loading & submission by default

The recent patch
. fce91f22 drm/i915/guc: add enable_guc_loading parameter
enabled GuC loading and submission by default, but as issues
were found with warnings being issued during suspend-resume
cycles, GuC loading was disabled by default, by patch
. 2335986d

 drm/i915/guc: Disable automatic GuC firmware loading

Those warnings have been resolved, so this patch re-enables GuC
loading and submission by default.

Signed-off-by: Dave Gordon <david.s.gordon@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1465287291-2187-1-git-send-email-david.s.gordon@intel.com