HV: Refine 'hv_main()' function usage

'hv_main()' wraps several logic which has no dependencies
   each other(enable VMX, prepare to create service os VM..),
   in this case, split this function to make code logic clear.

   remove 'is_vm0_bsp()' & 'hv_main()'
Signed-off-by: Yonghua Huang <yonghua.huang@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>

hypervisor/common/hypercall.c

@@ -161,9 +161,6 @@ int32_t hcall_create_vm(struct vm *vm, uint64_t param)
 {
 	int32_t ret = 0;
 	struct vm *target_vm = NULL;
-	/* VM are created from hv_main() directly
-	 * Here we just return the vmid for DM
-	 */
 	struct acrn_create_vm cv;
 	struct vm_description vm_desc;