drm/amd/pp: fix missing CONFIG_ACPI.

This was stopping me building on ARM after last pull.
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/amd/powerplay/hwmgr/smu7_hwmgr.c

@@ -3827,12 +3827,14 @@ static int smu7_notify_link_speed_change_after_state_change(
 				smu7_get_current_pcie_speed(hwmgr) > 0)
 			return 0;
 
+#ifdef CONFIG_ACPI
 		if (amdgpu_acpi_pcie_performance_request(hwmgr->adev, request, false)) {
 			if (PP_PCIEGen2 == target_link_speed)
 				pr_info("PSPP request to switch to Gen2 from Gen3 Failed!");
 			else
 				pr_info("PSPP request to switch to Gen1 from Gen2 Failed!");
 		}
+#endif
 	}
 
 	return 0;