cifs: don't leak -ENOMEM in smb2_open_file()

cifs: don't leak -ENOMEM in smb2_open_file()

[ Upstream commit f60ffa662d1427cfd31fe9d895c3566ac50bfe52 ]

A NULL error response might be a valid case where smb2_reconnect()
failed to reconnect the session and tcon due to a disconnected server
prior to issuing the I/O operation, so don't leak -ENOMEM to userspace
on such occasions.

Fixes: 76894f3e2f71 ("cifs: improve symlink handling for smb2+")
Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>