serial: related to bz#888694: qga fails after resume from s3.
serial: related to bz#888694: qga fails after resume from s3.

The qga service doesn't recover from a read error (from serial port) and
virtio-serial driver cancel all pending read requests when the system was
put to sleep.

The driver behavior was changed to not cancel pending read requests. In
addition the "guest connected" and "removed" status update was moved to
the (hopefully) appropriate locations in the power events callbacks.

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