drm/amdgpu: work around lack of upstream ACPI support for D3cold

Until Dave's patch to support the new hybrid gfx ACPI method goes
upstream, we can fallback to the old ATPX method which seems to
still work.
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_atpx_handler.c

@@ -200,7 +200,16 @@ static int amdgpu_atpx_validate(struct amdgpu_atpx *atpx)
 	atpx->is_hybrid = false;
 	if (valid_bits & ATPX_MS_HYBRID_GFX_SUPPORTED) {
 		printk("ATPX Hybrid Graphics\n");
+#if 1
+		/* This is a temporary hack until the D3 cold support
+		 * makes it upstream.  The ATPX power_control method seems
+		 * to still work on even if the system should be using
+		 * the new standardized hybrid D3 cold ACPI interface.
+		 */
+		atpx->functions.power_cntl = true;
+#else
 		atpx->functions.power_cntl = false;
+#endif
 		atpx->is_hybrid = true;
 	}