This patch adds support to add mpls multipath
routes.

example:
ip -f mpls route add 100 \
	nexthop as 200 via inet 10.1.1.2 dev swp1 \
	nexthop as 700 via inet 10.1.1.6 dev swp2
Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>