x86: call cache_add_dev() from cache_sysfs_init() explicitly
Call cache_add_dev() from cache_sysfs_init() explicitly, instead of
referencing the CPU notifier callback directly from generic startup
code. Looks cleaner (to me at least) this way, and also makes it
possible to use other tricks to replace __cpuinit{data} annotations, as
recently discussed on this list.