kvmclock: remove unneeded EXPORT macro

check_and_clear_guest_paused does not need to be exported as it isn't used
by any modules, remove the export.

Signed-off-by: Eric B Munson <emunson@mgebm.net>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>