IA64: make the fpswa emulation keep the previous behaviour.

IA64: make the fpswa emulation keep the previous behaviour.

When fpswa library return statue > 0, keep the previous behavior.
This case should be addressed somehow later, but it seems somewhat
difficult to resolve, so keep the previous behavor for now.
It is assumed that a guest kernel calls fpswa library
without preemption. This assumption breaks if a guest kernel is
preemptive.

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>