mpls: always set type RTN_UNICAST and scope RT_SCOPE_UNIVERSE for

mpls: always set type RTN_UNICAST and scope RT_SCOPE_UNIVERSE for

This patch fixes incorrect -EINVAL errors due to invalid
scope and type during mpls route deletes.

$ip -f mpls route add 100 as 200 via inet 10.1.1.2 dev swp1

$ip -f mpls route show
100 as to 200 via inet 10.1.1.2 dev swp1

$ip -f mpls route del 100 as 200 via inet 10.1.1.2 dev swp1
RTNETLINK answers: Invalid argument

$ip -f mpls route del 100
RTNETLINK answers: Invalid argument

After patch:

$ip -f mpls route show
100 as to 200 via inet 10.1.1.2 dev swp1

$ip -f mpls route del 100 as 200 via inet 10.1.1.2 dev swp1

$ip -f mpls route show

Always set type to RTN_UNICAST for mpls route add/deletes.
Also to keep things consistent with kernel set scope to
RT_SCOPE_UNIVERSE for both mpls and ipv6 routes. Both mpls and ipv6 route
deletes ignore scope.

Suggested-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: Vivek Venkataraman <vivek@cumulusnetworks.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>