media: amphion: Fix error handling in vpu_driver_init()

A problem about modprobe amphion-vpu failed is triggered with the
following log given:

 [ 2208.634841] Error: Driver 'amphion-vpu' is already registered, aborting...
 modprobe: ERROR: could not insert 'amphion_vpu': Device or resource busy

The reason is that vpu_driver_init() returns vpu_core_driver_init()
directly without checking its return value, if vpu_core_driver_init()
failed, it returns without unregister amphion_vpu_driver, resulting the
amphion-vpu can never be installed later.
A simple call graph is shown as below:

 vpu_driver_init()
   platform_driver_register() # register amphion_vpu_driver
   vpu_core_driver_init()
     platform_driver_register()
       driver_register()
         bus_add_driver()
           dev = kzalloc(...) # OOM happened
   # return without unregister amphion_vpu_driver

Fix by unregister amphion_vpu_driver when vpu_core_driver_init() returns
error.

Fixes: b50a64fc ("media: amphion: add amphion vpu device driver")
Signed-off-by: Yuan Can <yuancan@huawei.com>
Reviewed-by: ming_qian <ming.qian@nxp.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

drivers/media/platform/amphion/vpu_drv.c

@@ -245,7 +245,11 @@ static int __init vpu_driver_init(void)
 	if (ret)
 		return ret;
 
-	return vpu_core_driver_init();
+	ret = vpu_core_driver_init();
+	if (ret)
+		platform_driver_unregister(&amphion_vpu_driver);
+
+	return ret;
 }
 
 static void __exit vpu_driver_exit(void)