commit 69d9cd8c upstream.

This reverts commit 7291a932.

The conversion to be16_add_cpu() is incorrect in case cryptlen is
negative due to premature (i.e. before addition / subtraction)
implicit conversion of cryptlen (int -> u16) leading to sign loss.

Cc: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Horia Geanta <horia.geanta@freescale.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>