LF-9318: drm: bridge: cdns_hdmi: add bpc check for iMX8QM

commit 54945bc1ef7ae2c3f584cc7e099b174d636dc2a4 from
https://github.com/nxp-imx/linux-imx.git



On iMX8QM only bpc less than 12 is supported.
Add bpc check to avoid exceed SOC capability.

Signed-off-by: Sandor Yu <Sandor.yu@nxp.com>
Reviewed-by: Robby Cai <robby.cai@nxp.com>
Signed-off-by: Xiaolei Wang <xiaolei.wang@windriver.com>