drm/i915: Spell out IS_HSW/BDW_ULT() in intel_crt_present()

The quality of being a ULT or ULX package doesn't tell anything across
generations and so a global IS_ULT() macro doesn't make much sense, esp.
as we're adding new products.

So, spell out which ULT/ULX SKUs we are talking about here, namely HSW
and BDW.

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>