[olsr] Bump olsr version to 0.9.6.2

[olsr] Bump olsr version to 0.9.6.2

This patch bumps olsr version from 0.9.6.1 to 0.9.6.2
One major bugfix comes with the newer version, which is quite relevant
for our Freifunk mesh network: the feature LinkQualityMult was not
working in 0.9.6.1 and got fixed in the new version.

Tested on 92 productive mesh nodes running current LEDE trunk .

Signed-off-by: Thomas Huehn <thomas@net.t-labs.tu-berlin.de>