tools: Synchronize tools/include/uapi/linux/bpf.h

Commit 747ea55e4f78 ("bpf: fix bpf_skb_in_cgroup helper naming") renames
BPF_FUNC_skb_in_cgroup to bpf_skb_under_cgroup, triggering this warning
while building perf:

Warning: tools/include/uapi/linux/bpf.h differs from kernel

Update the copy to ack that, no changes needed, as
BPF_FUNC_skb_in_cgroup isn't used so far.

Cc: Adrian Hunter <[e-mail]>
Cc: Daniel Borkmann <[e-mail]>
Cc: David Ahern <[e-mail]>
Cc: David S. Miller <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Wang Nan <[e-mail]>
Link: http://lkml.kernel.org/n/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/include/uapi/linux/bpf.h

···
 	BPF_FUNC_skb_change_type,
 
 	/**
-	 * bpf_skb_in_cgroup(skb, map, index) - Check cgroup2 membership of skb
+	 * bpf_skb_under_cgroup(skb, map, index) - Check cgroup2 membership of skb
 	 * @skb: pointer to skb
 	 * @map: pointer to bpf_map in BPF_MAP_TYPE_CGROUP_ARRAY type
 	 * @index: index of the cgroup in the bpf_map
···
 	 *   == 1 skb succeeded the cgroup2 descendant test
 	 *    < 0 error
 	 */
-	BPF_FUNC_skb_in_cgroup,
+	BPF_FUNC_skb_under_cgroup,
 
 	/**
 	 * bpf_get_hash_recalc(skb)