drm/i915: Add enabledisable()

'enable ? "enable" : "disable"' is a fairly common pattern in
our debug prints. Let's introduce a helper for it.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210416171011.19012-8-ville.syrjala@linux.intel.com


Reviewed-by: Jani Nikula <jani.nikula@intel.com>