drm/i915: split out display quirks to a new file

Reduce intel_display.c by splitting out intel_quirks.c. No functional
changes.

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181016144228.18267-1-jani.nikula@intel.com