net: icmpv4: fix broadcast ping reply bug
net: icmpv4: fix broadcast ping reply bug

If `CONFIG_NET_ICMPV4_ACCEPT_BROADCAST` is enabled ICMPv4 should reply
to request packets sent to the broadcast address of an interface with
the unicast address of that interface from the same subnet.

Previously the code blindly copied the ICMP source address which meant
it would reply to broadcast packets with a broadcast source address.

Signed-off-by: Arvin Farahmand <4208c8ae77e6dd3ecebee6cbd1512b26823ef0ce@ip-logix.com>

finikorg/zephyr,galak/zephyr,finikorg/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,galak/zephyr,galak/zephyr,Vudentz/zephyr,Vudentz/zephyr,nashif/zephyr,galak/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,nashif/zephyr,Vudentz/zephyr,finikorg/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr