x86/vm_event: consolidate hvm_event_fill_regs and p2m_vm_event_fill_regs

x86/vm_event: consolidate hvm_event_fill_regs and p2m_vm_event_fill_regs

Currently the registers saved in the request depend on which type of event
is filling in the registers. In this patch we consolidate the two versions
of register filling function as to return a fix set of registers irrespective
of the underlying event.

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