drm/i915/gt: Include the engine's fw-domains in the debug info

Add engine->fw_domain/active to the pretty printer for debug dumps and
debugfs.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Venkata Sandeep Dhanalakota <venkata.s.dhanalakota@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200605144705.31127-1-chris@chris-wilson.co.uk