drm/i915: Fix HTI port checking

There was some misinterpretation of specification, when DDIX_USED is
set, the next bit means 0 for DP and 1 for HDMI.

Anyways this misinterpretation is not causing any issues, this change
is just to comply with specification.
Also as for us it do not matters if it is HDMI or DP, not checking the
port type that HTI is using.

Cc: Anusha Srivatsa <anusha.srivatsa@intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210108134802.21280-1-jose.souza@intel.com