drm/amd/display: Remove OTG DIV register write for Virtual signals.

[WHY]
Hot plugging and then hot unplugging leads to k1 and k2 values to
change, as signal is detected as a virtual signal on hot unplug. Writing
these values to OTG_PIXEL_RATE_DIV register might cause primary display
to blank (known hw bug).

[HOW]
No longer write k1 and k2 values to register if signal is virtual, we
have safe guards in place in the case that k1 and k2 is unassigned so
that an unknown value is not written to the register either.

Cc: [email protected]
Cc: Mario Limonciello <[email protected]>
Reviewed-by: Samson Tam <[email protected]>
Reviewed-by: Alvin Lee <[email protected]>
Acked-by: Qingqing Zhuo <[email protected]>
Signed-off-by: Saaem Rizvi <[email protected]>
Tested-by: Daniel Wheeler <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>

Author: Saaem Rizvi

drivers/gpu/drm/amd/display/dc/dcn32/dcn32_hwseq.c

@@ -1104,7 +1104,7 @@ unsigned int dcn32_calculate_dccg_k1_k2_values(struct pipe_ctx *pipe_ctx, unsign
 			*k2_div = PIXEL_RATE_DIV_BY_2;
 		else
 			*k2_div = PIXEL_RATE_DIV_BY_4;
-	} else if (dc_is_dp_signal(stream->signal) || dc_is_virtual_signal(stream->signal)) {
+	} else if (dc_is_dp_signal(stream->signal)) {
 		if (two_pix_per_container) {
 			*k1_div = PIXEL_RATE_DIV_BY_1;
 			*k2_div = PIXEL_RATE_DIV_BY_2;