KVM: selftests: Remove vcpu_get() usage from dirty_log_test

Grab the vCPU from vm_vcpu_add() directly instead of doing vcpu_get()
after the fact.  This will allow removing vcpu_get() entirely.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

tools/testing/selftests/kvm/dirty_log_test.c

@@ -665,7 +665,7 @@ static void vm_dirty_log_verify(enum vm_guest_mode mode, unsigned long *bmap)
 	}
 }
 
-static struct kvm_vm *create_vm(enum vm_guest_mode mode, uint32_t vcpuid,
+static struct kvm_vm *create_vm(enum vm_guest_mode mode, struct kvm_vcpu **vcpu,
 				uint64_t extra_mem_pages, void *guest_code)
 {
 	struct kvm_vm *vm;
@@ -676,7 +676,7 @@ static struct kvm_vm *create_vm(enum vm_guest_mode mode, uint32_t vcpuid,
 	vm = __vm_create(mode, DEFAULT_GUEST_PHY_PAGES + extra_pg_pages);
 
 	log_mode_create_vm_done(vm);
-	vm_vcpu_add(vm, vcpuid, guest_code);
+	*vcpu = vm_vcpu_add(vm, 0, guest_code);
 	return vm;
 }
 
@@ -710,10 +710,8 @@ static void run_test(enum vm_guest_mode mode, void *arg)
 	 * (e.g., 64K page size guest will need even less memory for
 	 * page tables).
 	 */
-	vm = create_vm(mode, 0,
-		       2ul << (DIRTY_MEM_BITS - PAGE_SHIFT_4K),
-		       guest_code);
-	vcpu = vcpu_get(vm, 0);
+	vm = create_vm(mode, &vcpu,
+		       2ul << (DIRTY_MEM_BITS - PAGE_SHIFT_4K), guest_code);
 
 	guest_page_size = vm_get_page_size(vm);
 	/*