include: zephyr: sys: time_units: Type cast SYS_CLOCK_HW_CYCLES_PER_SEC

Type case CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC to uint32_t
while defining sys_clock_hw_cycles_per_sec_runtime_get()
to extend the range of frequency to 0xffffffff.

Signed-off-by: Anisetti Avinash Krishna <anisetti.avinash.krishna@intel.com>