net: stats: Simplify periodic statistics printing
net: stats: Simplify periodic statistics printing

Use modular arithmetic in statistics prints so that wraparounds are
automatically handled.

Signed-off-by: Jukka Rissanen <f9f077d1da4c7aa947f9864fa5a28c3588f6a45d@linux.intel.com>

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