staging:ccg: fix a class_destroy when kmalloc fails after the class_create

we do class_create and call kmalloc to allocate dev pointer,
and if kmalloc fail we forget destoying class

Signed-off-by: Devendra Naga <devendra.aaru@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>