Always make sysfs read-write with privileged

It does not make any sense to vary this based on whether the
rootfs is read only. We removed all the other mount dependencies
on read-only eg see #35344.

Signed-off-by: Justin Cormack <justin.cormack@docker.com>

daemon/oci_linux.go

@@ -685,12 +685,10 @@ func setMounts(daemon *Daemon, s *specs.Spec, c *container.Container, mounts []c
 	}
 
 	if c.HostConfig.Privileged {
-		if !s.Root.Readonly {
-			// clear readonly for /sys
-			for i := range s.Mounts {
-				if s.Mounts[i].Destination == "/sys" {
-					clearReadOnly(&s.Mounts[i])
-				}
+		// clear readonly for /sys
+		for i := range s.Mounts {
+			if s.Mounts[i].Destination == "/sys" {
+				clearReadOnly(&s.Mounts[i])
 			}
 		}
 		s.Linux.ReadonlyPaths = nil

integration-cli/docker_cli_run_test.go

@@ -2688,7 +2688,7 @@ func (s *DockerSuite) TestRunContainerWithReadonlyRootfs(c *check.C) {
 	if root := os.Getenv("DOCKER_REMAP_ROOT"); root != "" {
 		testPriv = false
 	}
-	testReadOnlyFile(c, testPriv, "/file", "/etc/hosts", "/etc/resolv.conf", "/etc/hostname", "/sys/kernel")
+	testReadOnlyFile(c, testPriv, "/file", "/etc/hosts", "/etc/resolv.conf", "/etc/hostname")
 }
 
 func (s *DockerSuite) TestPermissionsPtsReadonlyRootfs(c *check.C) {