Drivers: hv: utils: Use TimeSync samples to adjust the clock after boot.

Drivers: hv: utils: Use TimeSync samples to adjust the clock after boot.

BugLink: http://bugs.launchpad.net/bugs/1650059
Only the first 50 samples after boot were being used to discipline the
clock. After the first 50 samples, any samples from the host were ignored
and the guest clock would eventually drift from the host clock.

This patch allows TimeSync-enabled guests to continuously synchronize the
clock with the host clock, even after the first 50 samples.

Signed-off-by: Alex Ng <alexng@messages.microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 2e338f7e034f12066c78999deff8894c337ae23b)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Acked-by: Brad Figg <brad.figg@canonical.com>
Acked-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>