drm/i915/dp: Optimize the FRL configuration for HDMI2.1 PCON

Currently the HDMI2.1 PCON's frl link config DPCD registers are
reset and configured even if they are already configured.
Also the HDMI Link Mode does not settle to FRL MODE immediately after
HDMI Link Status is active.

This patch:
-Checks if the PCON is already configured for FRL.
-Include HDMI Link Mode in wait for loop along with HDMI Link status DPCD.

v2: Rebase

Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Uma Shankar <uma.shankar@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211110072947.171659-2-ankit.k.nautiyal@intel.com