target/arm/kvm: Unexport and tidy kvm_arm_sync_mpstate_to_{kvm, qemu}

target/arm/kvm: Unexport and tidy kvm_arm_sync_mpstate_to_{kvm, qemu}

Drop fprintfs and actually use the return values in the callers.
This is OK to do since commit 7191f24c7fcf which added the
error-check to the generic accel/kvm functions that eventually
call into these ones.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
[PMM: tweak commit message]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>