hv:remove some unnecessary includes

--remove unnecessary includes
--remove unnecssary forward-declaration for 'struct vhm_request'

Tracked-On: #861
Signed-off-by: Mingqiang Chi <mingqiang.chi@intel.com>

hypervisor/dm/vpci/pci_pt.c

@@ -27,10 +27,8 @@
 * $FreeBSD$
 */
 #include <vm.h>
-#include <errno.h>
 #include <ept.h>
 #include <mmu.h>
-#include <vmx.h>
 #include <logmsg.h>
 #include "vpci_priv.h"