crypto: talitos - Preempt overflow interrupts off-by-one fix

In commit ec6644d6 "crypto: talitos - Preempt
overflow interrupts", the test in atomic_inc_not_zero was interpreted by the
author to be applied after the increment operation (not before). This off-by-one
fix prevents overflow error interrupts from occurring when requests are frequent
and large enough to do so.

Signed-off-by: Vishnu Suresh <Vishnu@freescale.com>
Signed-off-by: Kim Phillips <kim.phillips@freescale.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>