smbd: Stop using vfs_Chdir after SMB_VFS_DISCONNECT.

smbd: Stop using vfs_Chdir after SMB_VFS_DISCONNECT.

This sequencing is causing problems for vfs_ceph, and likely
other vfs modules.

Signed-off-by: Ira Cooper <ira@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Autobuild-User(master): Jeremy Allison <jra@samba.org>
Autobuild-Date(master): Fri Jan 16 00:13:17 CET 2015 on sn-devel-104

(cherry picked from commit 81464daea71e5fa3067ec7d5f5c69c890c0f7949)

BUG: https://bugzilla.samba.org/show_bug.cgi?id=11115
S3: vfs_Chdir() is called after SMB_VFS_DISCONNECT in
source3/smbd/service.c::close_cnum().

Autobuild-User(v4-0-test): Karolin Seeger <kseeger@samba.org>
Autobuild-Date(v4-0-test): Mon Mar  2 23:25:27 CET 2015 on sn-devel-104