drm/i915/dp: Remove support for UHBR13.5

UHBR13.5 is not supported in MTL and also the DP2.1 spec says UHBR13.5
is optional. Hence removing UHBR135 from the supported link rates.

v2: Reframed the commit message and added link to the issue.

Signed-off-by: Arun R Murthy <arun.r.murthy@intel.com>
Fixes: 62618c7f

 ("drm/i915/mtl: C20 PLL programming")
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Animesh Manna <animesh.manna@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240228144350.3184930-1-arun.r.murthy@intel.com