vmevent: reduce include dependencies

vmevent: reduce include dependencies

There's no need for virtually everything to include public/vm_event.h.
Move its inclusion out of sched.h. This requires using the non-typedef
name in p2m_mem_paging_resume()'s prototype; by not changing the
function definition at the same time it'll remain certain that the build
would fail if the typedef itself was changed.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Reviewed-by: Alexandru Isaila <aisaila@bitdefender.com>
Acked-by: Tamas K Lengyel <tamas@tklengyel.com>