bug 7599 improving perf of ucast mac learning

bug 7599 improving perf of ucast mac learning

when the device is connected all its macs are learnt in one update.
node.merge is called for each local ucast and remote ucast mac.
Now it is called only once.

when a mac update comes its physical locator need not be part of the
same update. If the locator is not available in the same update get
it from the cache ( which got filled from previous locators update msg).

Change-Id: Idbcf0b881b8ac90526f400c5d17d56a825f0a611
Signed-off-by: K.V Suneelu Verma <k.v.suneelu.verma@ericsson.com>