ice: Simplify memory allocation in ice_sched_init_port()

'buf' is locale to the ice_sched_init_port() function.
There is no point in using devm_kzalloc()/devm_kfree().

use kzalloc()/kfree() instead.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>