drm/amd/display: Manually adjust strobe for DCN303

drm/amd/display: Manually adjust strobe for DCN303

commit a9a1ac44074ff8cab7d519277f93341e14557f83 upstream.

why:
DCN303's 4 channel SOC BB causes problems at strobe

how:
workaround to manually adjust strobe calculation using FCLK
restrict.

Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Agustin Gutierrez <agustin.gutierrez@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Martin Leung <Martin.Leung@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>