Remove unsupported lcow.vhdx option

Signed-off-by: John Howard <jhoward@microsoft.com>

This was only experimental and removed from opengcs. Making same
change in docker.

daemon/graphdriver/lcow/lcow.go

@@ -43,10 +43,6 @@
 //        -- Possible values:      Any valid linux kernel boot options
 //        -- Default if omitted:  <nil>
 //
-//   * lcow.vhdx - Specifies a custom vhdx file to boot (instead of a kernel+initrd)
-//        -- Possible values:      Any valid filename
-//        -- Default if omitted:  uvm.vhdx under `lcow.kirdpath`
-//
 //   * lcow.timeout - Specifies a timeout for utility VM operations in seconds
 //        -- Possible values:      >=0
 //        -- Default if omitted:  300

daemon/start_windows.go

@@ -33,8 +33,6 @@ func (daemon *Daemon) getLibcontainerdCreateOptions(container *container.Contain
 				config.KernelFile = v
 			case "lcow.initrd":
 				config.InitrdFile = v
-			case "lcow.vhdx":
-				config.Vhdx = v
 			case "lcow.bootparameters":
 				config.BootParameters = v
 			}

libcontainerd/local/local_windows.go

@@ -393,21 +393,12 @@ func (c *client) createLinux(id string, spec *specs.Spec, runtimeOptions interfa
 		ContainerType:               "linux",
 		Owner:                       defaultOwner,
 		TerminateOnLastHandleClosed: true,
-	}
-
-	if lcowConfig.ActualMode == opengcs.ModeActualVhdx {
-		configuration.HvRuntime = &hcsshim.HvRuntime{
-			ImagePath:          lcowConfig.Vhdx,
-			BootSource:         "Vhd",
-			WritableBootSource: false,
-		}
-	} else {
-		configuration.HvRuntime = &hcsshim.HvRuntime{
+		HvRuntime: &hcsshim.HvRuntime{
 			ImagePath:           lcowConfig.KirdPath,
 			LinuxKernelFile:     lcowConfig.KernelFile,
 			LinuxInitrdFile:     lcowConfig.InitrdFile,
 			LinuxBootParameters: lcowConfig.BootParameters,
-		}
+		},
 	}
 
 	if spec.Windows == nil {