ice: Make use of assign_bit() API

We have for some time the assign_bit() API to replace open coded

    if (foo)
            set_bit(n, bar);
    else
            clear_bit(n, bar);

Use this API to clean the code. No functional change intended.

Signed-off-by: Hongbo Li <lihongbo22@huawei.com>
Reviewed-by: Gerhard Engleder <gerhard@engleder-embedded.com>
Tested-by: George Kuruvinakunnel <george.kuruvinakunnel@intel.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>