ice: use min_t() to make code cleaner in ice_gnss

Fix the following coccicheck warning:
./drivers/net/ethernet/intel/ice/ice_gnss.c:79:26-27: WARNING opportunity for min()

Signed-off-by: Wan Jiabing <wanjiabing@vivo.com>
Tested-by: Gurucharan <gurucharanx.g@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>