soc: arm: select CPU_HAS_SYSTICK in ARCH Kconfig

ARM SysTick timer is implemented by default in ARMv7-M
and Mainline ARMv8-M processors, so we include the
corresponding Kconfig symbol in arch/arm/core/cortex-M/Kconfig
and remove the selections from the Cortex-M SOCs.

Signed-off-by: Ioannis Glaropoulos <Ioannis.Glaropoulos@nordicsemi.no>