MFC: r228218, r228219, 228220, 228221

Rename copyin_timeout32 to umtx_copyin_timeout32 and move parameter
check here. Include check for negative seconds value.
Add umtx_copyin_timeout() and move parameter checks here.
Add declaration of umtx_copyin_timeout()
Use umtx_copyin_timeout() to copy and check timeout parameteri in
kern_thr_suspend().