net: icmp: Verify the address family before calling the callback

Check the address family of the packet before passing it to a ICMP
handler, to avoid scenarios where ICMPv4 packet is paseed to a ICMPv6
handler and vice versa.

Signed-off-by: Robert Lubos <robert.lubos@nordicsemi.no>
(cherry picked from commit 587d9e6a4a2d20e77093bc507a5d940f1b8fec9f)