ice: Fix pointer cast warnings

pointers should be casted to unsigned long to avoid
-Wpointer-to-int-cast warnings:

drivers/net/ethernet/intel/ice/ice_flow.h:197:33: warning:
    cast from pointer to integer of different size
drivers/net/ethernet/intel/ice/ice_flow.h:198:32: warning:
    cast to pointer from integer of different size

Signed-off-by: Bixuan Cui <cuibixuan@huawei.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>