ice: ensure the hardware Clock Generation Unit is configured

The E822 device has a Clock Generation Unit (CGU) responsible for
determining the clock frequency that drives the timers.

Ensure this function is initialized when bringing up the PTP support, so
that the clock has a known frequency.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Gurucharan G <gurucharanx.g@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>