seqlock: fix raw_read_seqcount_latch()

lockless_dereference() is supposed to take pointer not integer.

Link: http://lkml.kernel.org/r/20160521201448.GA7429@p183.telecom.by
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>