ipv4: icmp: Pass full DS field to ip_route_input()

Align the ICMP code to other callers of ip_route_input() and pass the
full DS field. In the future this will allow us to perform a route
lookup according to the full DSCP value.

No functional changes intended since the upper DSCP bits are masked when
comparing against the TOS selectors in FIB rules and routes.

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Guillaume Nault <gnault@redhat.com>
Acked-by: Florian Westphal <fw@strlen.de>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://patch.msgid.link/20240821125251.1571445-11-idosch@nvidia.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>