drm/amd/display: Add debug key to allow disabling dtbclk

[HOW]
Add debug key to allow disabling dtbclk

Reviewed-by: Charlene Liu <[e-mail]>
Acked-by: Alex Hung <[e-mail]>
Signed-off-by: Muhammad Ahmed <[e-mail]>
Tested-by: Daniel Wheeler <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/display/dc/clk_mgr/dcn35/dcn35_clk_mgr.c

···
 		}
 
 		if (clk_mgr_base->clks.dtbclk_en && !new_clocks->dtbclk_en) {
-			dcn35_smu_set_dtbclk(clk_mgr, false);
+			if (clk_mgr->base.ctx->dc->config.allow_0_dtb_clk)
+				dcn35_smu_set_dtbclk(clk_mgr, false);
 			clk_mgr_base->clks.dtbclk_en = new_clocks->dtbclk_en;
 		}
 		/* check that we're not already in lower */

drivers/gpu/drm/amd/display/dc/dc.h

···
 	unsigned int disable_ips;
 	unsigned int disable_ips_in_vpb;
 	bool usb4_bw_alloc_support;
+	bool allow_0_dtb_clk;
 };
 
 enum visual_confirm {