drm/i915/display/lspcon: Increase LSPCON mode settle timeout

drm/i915/display/lspcon: Increase LSPCON mode settle timeout

This is to eliminate all cases of "*ERROR* LSPCON mode hasn't settled",
followed by link training errors. Intel engineers recommended increasing
this timeout and that does resolve the issue.

On some CometLake-based device designs the Parade PS175 takes more than
400ms to settle in PCON mode. 100 reboot trials on one device resulted
in a median settle time of 440ms and a maximum of 444ms. Even after
increasing the timeout to 500ms, 2% of devices still had this error. So
this increases the timeout to 800ms.

Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/9443
Signed-off-by: Pablo Ceballos <pceballos@google.com>
Signed-off-by: Niko Tsirakis <ntsirakis@google.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231002204709.761089-1-ntsirakis@google.com