cifs: Fix missing error code set

In cifs_strict_readv(), the default rc (-EACCES) is accidentally cleared by
a successful return from netfs_start_io_direct(), such that if
cifs_find_lock_conflict() fails, we don't return an error.

Fix this by resetting the default error code.

Fixes: 14b1cd25

 ("cifs: Fix locking in cifs_strict_readv()")
Cc: stable@vger.kernel.org
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Paulo Alcantara (Red Hat) <pc@manguebit.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: linux-cifs@vger.kernel.org
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>