drm/amd/display: add support for three new square pattern variants from DP2.1 specs

[why]
DP2.1 specs has brought 3 new variants of sqaure patterns with different
pre-shoot and de-emphasis equalization requirements. The commit adds
logic to identify these variants and apply corresponding eqaulization
requirements into hardware lane settings.

Reviewed-by: George Shen <George.Shen@amd.com>
Acked-by: Jasdeep Dhillon <jdhillon@amd.com>
Signed-off-by: Wenjing Liu <wenjing.liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>