gk20a_channel_release() should bail if filp->private_data is
NULL. This can happen as a result of gk20a_channel_release()
being called when __gk20a_channel_open() fails in
NVHOST_IOCTL_CHANNEL_OPEN.
Bug 200014898
Change-Id: I32cc957aca46fcd4265a8052ac5be355b644b9f7
Signed-off-by: Aingara Paramakuru <aparamakuru@nvidia.com>
Reviewed-on: http://git-master/r/496138
Reviewed-by: Ken Adams <kadams@nvidia.com>
Tested-by: Ken Adams <kadams@nvidia.com>