The multibuffer hash speed test is incorrectly bailing because
of an EINPROGRESS return value.  This patch fixes it by setting
ret to zero if it is equal to -EINPROGRESS.
Reported-by: NMegha Dey <megha.dey@linux.intel.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>