drm/amd/display: Set DISPCLK_MAX_ERRDET_CYCLES to 7

[WHY]
DISPCLK_MAX_ERRDET_CYCLES must be 7 to prevent connection loss when
changing DENTIST_DISPCLK_WDIVIDER from 126 to 127 and back.

Signed-off-by: Wesley Chalmers <Wesley.Chalmers@amd.com>
Reviewed-by: Dmytro Laktyushkin <Dmytro.Laktyushkin@amd.com>
Acked-by: Stylon Wang <stylon.wang@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>