drm/edid: Parse MAX_FRL field from HFVSDB block

This patch parses MAX_FRL field to get the MAX rate in Gbps that
the HDMI 2.1 panel can support in FRL mode. Source need this
field to determine the optimal rate between the source and sink
during FRL training.

v2: Fixed minor bugs, and removed extra wrapper function (Uma Shankar)

Signed-off-by: Swati Sharma <swati2.sharma@intel.com>
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
[Jani: Fixed checkpatch FROM_SIGN_OFF_MISMATCH, PARENTHESIS_ALIGNMENT.]
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201218103723.30844-3-ankit.k.nautiyal@intel.com