Staging: hv: util: Adjust guest time in a process context

The current code was adjusting guest time in interrupt context; do this
in process context since we may have to initiate cross-processor
interrupts as part of setting time.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>