net/ipv6/ila/ila_xlat.c: simplify a strange allocation pattern

net/ipv6/ila/ila_xlat.c: simplify a strange allocation pattern

alloc_ila_locks seemed to c&p from alloc_bucket_locks allocation pattern
which is quite unusual.  The default allocation size is 320 *
sizeof(spinlock_t) which is sub page unless lockdep is enabled when the
performance benefit is really questionable and not worth the subtle code
IMHO.  Also note that the context when we call ila_init_net (modprobe or
a task creating a net namespace) has to be properly configured.

Let's just simplify the code and use kvmalloc helper which is a
transparent way to use kmalloc with vmalloc fallback.

Link: http://lkml.kernel.org/r/20170306103032.2540-5-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Tom Herbert <tom@herbertland.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>