drm/amd/display: Avoid turning off the PHY when OTG is running for DVI

drm/amd/display: Avoid turning off the PHY when OTG is running for DVI

[Why]
The OTG's virtual pixel clock source for DVI comes from the PHY.

If the signal type is DVI then the OTG can become stuck on pre DCN401
ASIC when DPMS off occurs because the OTG remains running but the
PHY transmitter is disabled.

[How]
There exists logic to keep track of the OTG running refcount on the
link to determine if the link needs to go to PLL_EN instead of TX_EN
but the logic only checks for HDMI TMDS on older ASIC.

DVI is still a TMDS signal type so the constraint should also apply.

Replace the checks for dc_is_hdmi_tmds_signal with dc_is_tmds_signal to
cover both HDMI and DVI for the symclk refcount workaround.

Reviewed-by: Dillon Varone <dillon.varone@amd.com>
Reviewed-by: Charlene Liu <charlene.liu@amd.com>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Chuanyu Tseng <chuanyu.tseng@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>