net/fq_impl: Switch to kvmalloc() for memory allocation

The FQ implementation used by mac80211 allocates memory using kmalloc(),
which can fail; and Johannes reported that this actually happens in
practice.

To avoid this, switch the allocation to kvmalloc() instead; this also
brings fq_impl in line with all the FQ qdiscs.

Fixes: 557fc4a09803 ("fq: add fair queuing framework")
Reported-by: Johannes Berg <[e-mail]>
Signed-off-by: Toke Høiland-Jørgensen <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Johannes Berg <[e-mail]>

include/net/fq_impl.h

···
 	fq->limit = 8192;
 	fq->memory_limit = 16 << 20; /* 16 MBytes */
 
-	fq->flows = kcalloc(fq->flows_cnt, sizeof(fq->flows[0]), GFP_KERNEL);
+	fq->flows = kvcalloc(fq->flows_cnt, sizeof(fq->flows[0]), GFP_KERNEL);
 	if (!fq->flows)
 		return -ENOMEM;
 
···
 	for (i = 0; i < fq->flows_cnt; i++)
 		fq_flow_reset(fq, &fq->flows[i], free_func);
 
-	kfree(fq->flows);
+	kvfree(fq->flows);
 	fq->flows = NULL;
 }