disp: msm: dp: use extended DPCD fields to configure dp link rate

Use the EXTENDED_RECEIVER_CAPABILITY DPCD register fields,
if present, for enabling HBR3 link rate on supported targets.

CRs-Fixed: 2438457
Change-Id: I505d998f31f79162dc290fc47fd9fbba51527982
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>