drm/i915/uc: Extract uc usage details into separate debugfs

It has been pointed out that information about HuC usage doesn't belong
in guc_info debugfs. Let's move "supported/used/wanted" matrix to a
separate debugfs file, keeping guc_info strictly about GuC.

Suggested-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Lukasz Fiedorowicz <lukasz.fiedorowicz@intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@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/20200708100843.297655-1-michal@hardline.pl