glusterd/snapshot: Correct the mount path check

Before removing a lvm, we check if the lvm is mounted
on the brick path. If not, we remove the brick path only.
Correcting this check to support restore cases, where the
volname is not the non-hyphanated uuid, but the original
volume's name.

Change-Id: If158f4651d36efa2f94523458faf826230e9c76a
BUG: 1113975
Signed-off-by: Avra Sengupta <asengupt@redhat.com>
Reviewed-on: http://review.gluster.org/8192
Reviewed-by: Vijaikumar Mallikarjuna <vmallika@redhat.com>
Tested-by: Justin Clift <justin@gluster.org>
Reviewed-by: Atin Mukherjee <amukherj@redhat.com>
Reviewed-by: Sachin Pandit <spandit@redhat.com>
Reviewed-by: Krishnan Parthasarathi <kparthas@redhat.com>
Tested-by: Krishnan Parthasarathi <kparthas@redhat.com>