bgpd: Fix missed unlocks

bgpd: Fix missed unlocks

When iterating over the bgp_dest table, using this pattern:

	for (dest = bgp_table_top(table); dest;
	     dest = bgp_route_next(dest)) {

If the code breaks or returns in the middle we will not have
properly unlocked the node as that bgp_table_top locks the top
dest and bgp_route_next locks the next dest and unlocks the old
dest.

From code inspection I have found a bunch of places that
we either return in the middle of or a break is issued.

Add appropriate unlocks.

Signed-off-by: Donald Sharp <sharpd@nvidia.com>