drm/amd/display: guard write a 0 post_divider value to HW

[why]
post_divider_value should not be 0.
Reviewed-by: Charlene Liu <charlene.liu@amd.com>
Signed-off-by: Ahmed, Muhammad <Ahmed.Ahmed@amd.com>
Signed-off-by: Zaeem Mohamed <zaeem.mohamed@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dccg/dcn35/dcn35_dccg.c

@@ -1082,6 +1082,7 @@ static void dccg35_trigger_dio_fifo_resync(struct dccg *dccg)
 	uint32_t dispclk_rdivider_value = 0;
 
 	REG_GET(DENTIST_DISPCLK_CNTL, DENTIST_DISPCLK_RDIVIDER, &dispclk_rdivider_value);
+	if (dispclk_rdivider_value != 0)
 		REG_UPDATE(DENTIST_DISPCLK_CNTL, DENTIST_DISPCLK_WDIVIDER, dispclk_rdivider_value);
 }