drm/dp_helper: Define options for FRL training for HDMI2.1 PCON

Currently the FRL training mode (Concurrent, Sequential) and
training type (Normal, Extended) are not defined properly and
are passed as bool values in drm_helpers for pcon
configuration for FRL training.

This patch:
-Add register masks for Sequential and Normal FRL training options.
-Fixes the drm_helpers for FRL Training configuration to use the
 appropriate masks.
-Modifies the calls to the above drm_helpers in i915/intel_dp as per
 the above change.

v2: Re-used the register masks for these options, instead of enum. (Ville)

Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210323112422.1211-2-ankit.k.nautiyal@intel.com