net: rpl: Move net_route_lookup to proper place
net: rpl: Move net_route_lookup to proper place

Route lookup is necessary only if life time is
NET_RPL_ZERO_LIFETIME, otherwise lookup not required.

Change-Id: I25fb85c53e2d43cfdce08411af385f3ae26384cc
Signed-off-by: Ravi kumar Veeramally <406c082aeb452858c41b213a757768e1c1dff29e@linux.intel.com>

fbsder/zephyr,fbsder/zephyr,fbsder/zephyr,fbsder/zephyr,fbsder/zephyr