bridge: br_arp_nd_proxy: set icmp6_router if neigh has NTF_ROUTER

bridge: br_arp_nd_proxy: set icmp6_router if neigh has NTF_ROUTER

BugLink: https://bugs.launchpad.net/bugs/1863019
[ Upstream commit 7aca011f88eb57be1b17b0216247f4e32ac54e29 ]

Fixes: ed842faeb2bd ("bridge: suppress nd pkts on BR_NEIGH_SUPPRESS ports")
Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>