drm/i915/adlp: Add MST short HBlank WA (Wa_14014143976)

drm/i915/adlp: Add MST short HBlank WA (Wa_14014143976)

Add a workaround to fix BS jitter issues on MST links if the HBLANK
period is less than 1 MTP. The WA applies only to UHBR rates while on
non-UHBR the specification requires disabling it explicitly - presumedly
because the register's reset value has the WA enabled.

Bspec: 50050, 55424

Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240129175533.904590-3-imre.deak@intel.com