Drivers: hv: balloon: Ensure pressure reports are posted regularly

commit ae339336dc950b9b05e7ccd3565dd3e8781c06d9 upstream.

The current code posts periodic memory pressure status from a dedicated thread.
Under some conditions, especially when we are releasing a lot of memory into
the guest, we may not send timely pressure reports back to the host. Fix this
issue by reporting pressure in all contexts that can be active in this driver.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>