[CIFS] mount of IPC$ breaks with iget patch

In looking at network named pipe support on cifs, I noticed that
Dave Howell's iget patch:

    iget: stop CIFS from using iget() and read_inode()

broke mounts to IPC$ (the interprocess communication share), and don't
handle the error case (when getting info on the root inode fails).

Thanks to Gunter who noted a typo in a debug line in the original
version of this patch.

CC: David Howells <dhowells@redhat.com>
CC: Gunter Kukkukk <linux@kukkukk.com>
CC: Stable Kernel <stable@kernel.org>
Signed-off-by: Steve French <sfrench@us.ibm.com>