drm/i915: Keep has_* in alphabetical order

As it already says in the comment block...

Signed-off-by: Michel Thierry <michel.thierry@intel.com>
Reviewed-by: Michał Winiarski <michal.winiarski@intel.com>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161206015704.12654-1-michel.thierry@intel.com