drm/i915: s/intel/hsw/ for hsw/bdw/skl buf trans

Give the hsw/bdw/skl buf trans stuff a better namespace.

Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210608073603.2408-2-ville.syrjala@linux.intel.com