ionic: Use an u16 for rx_copybreak

We only support (u16)-1 size for rx_copybreak, so we can reduce the
field size and move a couple other fields around to save a little
space in the ionic_lif struct.

Before:
	/* size: 17440, cachelines: 273, members: 56 */
	/* sum members: 17403, holes: 9, sum holes: 37 */
	/* last cacheline: 32 bytes */

After:
	/* size: 17424, cachelines: 273, members: 56 */
	/* sum members: 17401, holes: 7, sum holes: 23 */
	/* last cacheline: 16 bytes */

Signed-off-by: Brett Creeley <brett.creeley@amd.com>
Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Link: https://lore.kernel.org/r/20240619003257.6138-8-shannon.nelson@amd.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>