net: icmpv4: fix incorrect IP header checksum
net: icmpv4: fix incorrect IP header checksum

IPv4 header's checksum was set when 'setup_ipv4_header', but in that
times IPv4 header's source ip and dest ip address haven't setted. So
it may be set an incorrect checksum.

Fixes: #7989

Signed-off-by: qianfan Zhao <0d01fab1932da5a147025f14dd5829cf5bf10d4d@163.com>

zephyrproject-rtos/zephyr,punitvara/zephyr,galak/zephyr,punitvara/zephyr,GiulianoFranchetto/zephyr,finikorg/zephyr,zephyriot/zephyr,nashif/zephyr,ldts/zephyr,mbolivar/zephyr,explora26/zephyr,zephyrproject-rtos/zephyr,kraj/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,Vudentz/zephyr,ldts/zephyr,GiulianoFranchetto/zephyr,kraj/zephyr,Vudentz/zephyr,ldts/zephyr,explora26/zephyr,finikorg/zephyr,finikorg/zephyr,explora26/zephyr,GiulianoFranchetto/zephyr,zephyriot/zephyr,mbolivar/zephyr,kraj/zephyr,punitvara/zephyr,zephyriot/zephyr,ldts/zephyr,Vudentz/zephyr,Vudentz/zephyr,mbolivar/zephyr,nashif/zephyr,kraj/zephyr,nashif/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,kraj/zephyr,Vudentz/zephyr,explora26/zephyr,punitvara/zephyr,ldts/zephyr,nashif/zephyr,finikorg/zephyr,explora26/zephyr,punitvara/zephyr,galak/zephyr,GiulianoFranchetto/zephyr,zephyriot/zephyr,galak/zephyr,zephyriot/zephyr,mbolivar/zephyr,nashif/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,GiulianoFranchetto/zephyr,mbolivar/zephyr