vm_event: rename MEM_ACCESS_EMULATE and MEM_ACCESS_EMULATE_NOWRITE

vm_event: rename MEM_ACCESS_EMULATE and MEM_ACCESS_EMULATE_NOWRITE

By naming, placing and bit shift convention, it could be taken as
implied that MEM_ACCESS_EMULATE and MEM_ACCESS_EMULATE_NOWRITE are
mem_access event specific flags (instead of being generally
applicable as vm_event flags). This patch renames them to
VM_EVENT_FLAG_EMULATE and VM_EVENT_FLAG_EMULATE_NOWRITE
respectively, and uses bit shifts following the rest of the
VM_EVENT_FLAG_ constants.

Signed-off-by: Razvan Cojocaru <rcojocaru@bitdefender.com>
Acked-by: Tamas K Lengyel <tlengyel@novetta.com>