fix(eclass/cros-kernel/x86_64_defconfig) add pcnet32 support

This adds the two pcnet drivers to the kernel build, so that the image
will have working networking in a VirtualBox instance.
Merge pull request #15 from gregkh/virtualbox_fix

fix(eclass/cros-kernel/x86_64_defconfig) add pcnet32 support
Merge pull request #14 from gregkh/kernel-cleanup

Kernel versioning fixes