drm/i915/ddi: Add missing wait-for-active for HDMI aligning with bspec updates

After enabling DDI_BUF_CTL, wait for DDI_BUF_CTL to be active.
Bspec:4232,53339,49191,54145

Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221127052232.3942831-3-ankit.k.nautiyal@intel.com