bpf: Change kvfree to kfree in generic_map_lookup_batch()

buf_prevkey in generic_map_lookup_batch() is allocated with
kmalloc(). It's safe to free it with kfree().

Fixes: cb4d03ab499d ("bpf: Add generic support for lookup batch op")
Signed-off-by: Denis Efremov <[e-mail]>
Signed-off-by: Alexei Starovoitov <[e-mail]>
Acked-by: Song Liu <[e-mail]>
Link: https://lore.kernel.org/bpf/[e-mail]
Signed-off-by: Alexei Starovoitov <[e-mail]>

kernel/bpf/syscall.c

···
 
 	buf = kmalloc(map->key_size + value_size, GFP_USER | __GFP_NOWARN);
 	if (!buf) {
-		kvfree(buf_prevkey);
+		kfree(buf_prevkey);
 		return -ENOMEM;
 	}