serial: Replace KeStallExecutionProcessor with KeDelayExecutionThread
serial: Replace KeStallExecutionProcessor with KeDelayExecutionThread

Using KeDelayExecutionThread with zero timeout interval cause current thread
to relinquish the remainder of its time slice to other thread in most cases.
This allows to make small delay on PASSIVE_LEVEL and optimize CPU usage.
It looks slightly more efficient then using KeDelayExecutionThread which is
actually a busy loop.

Signed-off-by: Ilya Rudakov <8300843b273e1d997b2d119060a4420345621b2e@virtuozzo.com>

gnif/kvm-guest-drivers-windows,ladipro/kvm-guest-drivers-windows,virtio-win/kvm-guest-drivers-windows,YanVugenfirer/kvm-guest-drivers-windows,gnif/kvm-guest-drivers-windows,ladipro/kvm-guest-drivers-windows,vrozenfe/kvm-guest-drivers-windows,ladipro/kvm-guest-drivers-windows,virtio-win/kvm-guest-drivers-windows,daynix/kvm-guest-drivers-windows,gnif/kvm-guest-drivers-windows,YanVugenfirer/kvm-guest-drivers-windows,virtio-win/kvm-guest-drivers-windows,vrozenfe/kvm-guest-drivers-windows,daynix/kvm-guest-drivers-windows,daynix/kvm-guest-drivers-windows,YanVugenfirer/kvm-guest-drivers-windows,daynix/kvm-guest-drivers-windows,YanVugenfirer/kvm-guest-drivers-windows,virtio-win/kvm-guest-drivers-windows,gnif/kvm-guest-drivers-windows,vrozenfe/kvm-guest-drivers-windows,vrozenfe/kvm-guest-drivers-windows,virtio-win/kvm-guest-drivers-windows,vrozenfe/kvm-guest-drivers-windows,daynix/kvm-guest-drivers-windows,ladipro/kvm-guest-drivers-windows,YanVugenfirer/kvm-guest-drivers-windows