drm/amd/display: Add missing mask sh for SYM32_TP_SQ_PULSE register

There is a missing register mask in dcn32 causing the hardware
programming is not executed when programming SQ_num test pattern for
DP2.

Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Wenjing Liu <wenjing.liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>