remove ratelimt()

It mistakenly assumes that a static local in an inlined function is a
kernel-wide singleton.  It also has no callers, so let's remove it.

Cc: Dave Young <hidave.darkstar@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>