gpu: host1x: Fix memory leak of device names

In the Linux kernel, the following vulnerability has been resolved:

gpu: host1x: Fix memory leak of device names

The device names allocated by dev_set_name() need be freed before module unloading, but they can not be freed because the kobject's refcount which was set in device_initialize() has not be decreased to 0.

As comment of device_add() says, if it fails, use only put_device() drop the refcount, then the name will be freed in kobejct_cleanup().

device_del() and put_device() can be replaced with device_unregister(), so call it to unregister the added successfully devices, and just call put_device() to the not added device.

Add a release() function to device to avoid null release() function WARNING in device_release(), it's empty, because the context devices are freed together in host1x_memory_context_list_free().