drm/vmwgfx: Fix an uninitialized fence handle value

if vmw_execbuf_fence_commands() fails, The handle value will be
uninitialized and a bogus fence handle might be copied to user-space.

Cc: <stable@vger.kernel.org>
Fixes: 2724b2d5: ("drm/vmwgfx: Use new validation interface for the modesetting code v2")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Brian Paul <brianp@vmware.com> #v1
Reviewed-by: Sinclair Yeh <syeh@vmware.com> #v1
Reviewed-by: Deepak Rawat <drawat@vmware.com>

drivers/gpu/drm/vmwgfx/vmwgfx_kms.c

@@ -2554,8 +2554,8 @@ void vmw_kms_helper_validation_finish(struct vmw_private *dev_priv,
 				      user_fence_rep)
 {
 	struct vmw_fence_obj *fence = NULL;
-	uint32_t handle;
-	int ret;
+	uint32_t handle = 0;
+	int ret = 0;
 
 	if (file_priv || user_fence_rep || vmw_validation_has_bos(ctx) ||
 	    out_fence)