ice: use proper format for function pointer as a function parameter

Compiling with gcc-9.2.1 with W=1 points out warnings about the improper
function parameter list.  Fix it.
Signed-off-by: NBruce Allan <bruce.w.allan@intel.com>
Tested-by: NAndrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/ice/ice_xsk.c

@@ -609,7 +609,7 @@ ice_alloc_buf_slow_zc(struct ice_ring *rx_ring, struct ice_rx_buf *rx_buf)
  */
 static bool
 ice_alloc_rx_bufs_zc(struct ice_ring *rx_ring, int count,
-		     bool alloc(struct ice_ring *, struct ice_rx_buf *))
+		     bool (*alloc)(struct ice_ring *, struct ice_rx_buf *))
 {
 	union ice_32b_rx_flex_desc *rx_desc;
 	u16 ntu = rx_ring->next_to_use;