xenpaging: remove obsolete XENMEM_paging_op_resume

xenpaging: remove obsolete XENMEM_paging_op_resume

With changeset 24364:0964341efd65 an event channel based notification of
new responses in the ringbuffer is implemented. This makes the memevent
interface obsolete. Currently a call to p2m_mem_paging_resume() is
triggered twice by xenpaging, once per memevent and once per even
channel. In practice this double call does not lead to issues because
p2m_mem_paging_resume() processes only available events.

xenpaging used the event channel notification since the beginning, but
it was a no-op until changeset mentioned above. This change removes the
unneeded XENMEM_paging_op_resume functionality. Pagers are notified via
an event channel of new requests, and now they are required to notify
the hypervisor about their responses also with an event channel.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Tim Deegan <tim@xen.org>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>