drm/radeon: Call radeon_suspend_kms() in radeon_pci_shutdown() for Loongson64

On the Loongson64 platform used with Radeon GPU, shutdown or reboot failed
when console=tty is in the boot cmdline.

radeon_suspend_kms() puts the hw in the suspend state, especially set fb
state as FBINFO_STATE_SUSPENDED:

        if (fbcon) {
                console_lock();
                radeon_fbdev_set_suspend(rdev, 1);
                console_unlock();
        }

Then avoid to do any more fb operations in the related functions:

        if (p->state != FBINFO_STATE_RUNNING)
                return;

So call radeon_suspend_kms() in radeon_pci_shutdown() for Loongson64 to fix
this issue, it looks like some kind of workaround like powerpc.
Co-developed-by: Jianmin Lv <lvjianmin@loongson.cn>
Signed-off-by: Jianmin Lv <lvjianmin@loongson.cn>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

drivers/gpu/drm/radeon/radeon_drv.c

@@ -374,13 +374,13 @@ radeon_pci_shutdown(struct pci_dev *pdev)
 	if (radeon_device_is_virtual())
 		radeon_pci_remove(pdev);
 
-#ifdef CONFIG_PPC64
+#if defined(CONFIG_PPC64) || defined(CONFIG_MACH_LOONGSON64)
 	/*
 	 * Some adapters need to be suspended before a
 	 * shutdown occurs in order to prevent an error
-	 * during kexec.
-	 * Make this power specific becauase it breaks
-	 * some non-power boards.
+	 * during kexec, shutdown or reboot.
+	 * Make this power and Loongson specific because
+	 * it breaks some other boards.
 	 */
 	radeon_suspend_kms(pci_get_drvdata(pdev), true, true, false);
 #endif