fix(cros-kernel/x86_64_defconfig) enable vmware drivers

Build the vmware drivers so that machines can be properly managed on
those systems.
fix(cros-kernel/x86_64_defconfig) turn off SELINUX

SELinux does not need to be enabled in the kernel, so turn it off and
fall back to the "default" Linux security model
fix(cros-kernel/x86_64_defconfig) disable HOTPLUG_PCI

The kernel does not need HOTPLUG_PCI enabled, so turn it off, which
disables a number of other unneeded drivers as well.
Merge pull request #20 from gregkh/kernel_slimdown

Kernel slimdown