Bug 7295 - Incorrect handling of device transactions in clustered setting

Bug 7295 - Incorrect handling of device transactions in clustered setting

Transactions on mounted device in clustered setting are delegated to
leader node and leader node actually configures the device.

Implementation, hovewer, depens only on one transaction at a time.
Delegated calls can interleave together, for example one node can submit
transaction of the other node.

Explicitly open a new tranasction before applying any operations to it.

Change-Id: I0c5715a9cd089dd809b071d411884e71e9793849
Signed-off-by: Jakub Morvay <jmorvay@cisco.com>
(cherry picked from commit da599396d0581c113dba72b33f811c2a0d18ec9b)