drm/amd/display: Modify checks to enable TPS3 pattern when required

[HOW&WHY]
Checking if both DSC and FEC supported from sink and
source before going with TPS3 pattern during link
training.

Reviewed-by: Anthony Koo <Anthony.Koo@amd.com>
Acked-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Iswara Nagulendran <iswara.nagulendran@amd.com>
Tested-by: Mark Broadworth <mark.broadworth@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>