ice: Remove managed memory usage in ice_get_fw_log_cfg()

There is no need to use managed memory allocation here. The memory is
released at the end of the function.

Use kzalloc()/kfree() to simplify the code.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>