Fix for a -Wuninitialized compiler warning. Changed return value of
vmballoon_send_lock_page() from bool to int to be able to distinguish
between the error cases to avoid uninitialized use of hv_status in
vmballoon_reserve_page()
Signed-off-by: NDanny Kukawka <danny.kukawka@bisect.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>