drm: xlnx: hdmi: Add support to initialize FRL mode

commit  06c22789e0ed9110ea3f2b267f857ce95c0e4c21 from
https://github.com/Xilinx/linux-xlnx.git

 xlnx_rebase_v5.10

This patch adds the functions which are used to initialize the FRL mode.
This includes the FRL state machine which is as per the HDMI 2.1
specfication.

Signed-off-by: Venkateshwar Rao Gannavarapu <venkateshwar.rao.gannavarapu@xilinx.com>
State: pending
Signed-off-by: Quanyang Wang <quanyang.wang@windriver.com>