CPU: Introduce ARCH_HAS_CPU_AUTOPROBE and X86 parts

This patch is based on Andi Kleen's work:
Implement autoprobing/loading of modules serving CPU
specific features (x86cpu autoloading).

And Kay Siever's work to get rid of sysdev cpu structures
and making use of struct device instead.

Before, the cpuid driver had to be loaded to get the x86cpu
autoloading feature. With this patch autoloading works through
the /sys/devices/system/cpu object

Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Len Brown <lenb@kernel.org>
Acked-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Thomas Renninger <trenn@suse.de>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

include/linux/cpu.h

@@ -44,6 +44,13 @@ extern ssize_t arch_cpu_release(const char *, size_t);
 #endif
 struct notifier_block;
 
+#ifdef CONFIG_ARCH_HAS_CPU_AUTOPROBE
+extern int arch_cpu_uevent(struct device *dev, struct kobj_uevent_env *env);
+extern ssize_t arch_print_cpu_modalias(struct device *dev,
+				       struct device_attribute *attr,
+				       char *bufptr);
+#endif
+
 /*
  * CPU notifier priorities.
  */