drm/hisilicon/hibmc: Move drm_fbdev_generic_setup() down to avoid the splat

The HiSilicon hibmc driver triggers a splat at boot time as below

[   14.137806] ------------[ cut here ]------------
[   14.142405] hibmc-drm 0000:0a:00.0: Device has not been registered.
[   14.148661] WARNING: CPU: 0 PID: 496 at drivers/gpu/drm/drm_fb_helper.c:2233 drm_fbdev_generic_setup+0x15c/0x1b8
[   14.158787] [...]
[   14.278307] Call trace:
[   14.280742]  drm_fbdev_generic_setup+0x15c/0x1b8
[   14.285337]  hibmc_pci_probe+0x354/0x418
[   14.289242]  local_pci_probe+0x44/0x98
[   14.292974]  work_for_cpu_fn+0x20/0x30
[   14.296708]  process_one_work+0x1c4/0x4e0
[   14.300698]  worker_thread+0x2c8/0x528
[   14.304431]  kthread+0x138/0x140
[   14.307646]  ret_from_fork+0x10/0x18
[   14.311205] ---[ end trace a2000ec2d838af4d ]---

This turned out to be due to the fbdev device hasn't been registered when
drm_fbdev_generic_setup() is invoked. Let's fix the splat by moving it down
after drm_dev_register() which will follow the "Display driver example"
documented by commit de99f060 ("drm/drv: DOC: Add driver example
code").
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Xinliang Liu <xinliang.liu@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200706144713.1123-1-yuzenghui@huawei.com

drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c

@@ -307,8 +307,6 @@ static int hibmc_load(struct drm_device *dev)
 	/* reset all the states of crtc/plane/encoder/connector */
 	drm_mode_config_reset(dev);
 
-	drm_fbdev_generic_setup(dev, dev->mode_config.preferred_depth);
-
 	return 0;
 
 err:
@@ -355,6 +353,9 @@ static int hibmc_pci_probe(struct pci_dev *pdev,
 			  ret);
 		goto err_unload;
 	}
+
+	drm_fbdev_generic_setup(dev, dev->mode_config.preferred_depth);
+
 	return 0;
 
 err_unload: