extras/hookscripts: Fix set behaviour for user.cifs and user.smb

Setting either of user.cifs or user.smb to disable should disable smb
shares when the smb share is already available.

Change-Id: I213ffca9cedc14107daeb30271d1f41dd9d7fcf4
BUG: 1105147
Signed-off-by: Raghavendra Talur <rtalur@redhat.com>
Reviewed-on: http://review.gluster.org/9042
Reviewed-by: Lalatendu Mohanty <lmohanty@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Jose A. Rivera <jarrpa@redhat.com>
Reviewed-by: Krishnan Parthasarathi <kparthas@redhat.com>
Tested-by: Krishnan Parthasarathi <kparthas@redhat.com>