drm/i915: don't intel_crt_init on any ULT machines

We may have DDI_BUF_CTL(PORT_A) configured with 2 lanes and still not
have CRT, so just check for !IS_ULT. This problem happened on a real
machine and resulted in a very ugly dmesg.

Cc: stable@vger.kernel.org
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>