x86: handle PAT more like other CPU features

Impact: Cleanup

When PAT was originally introduced, it was handled specially for a few
reasons:

- PAT bugs are hard to track down, so we wanted to maintain a
  whitelist of CPUs.
- The i386 and x86-64 CPUID code was not yet unified.

Both of these are now obsolete, so handle PAT like any other features,
including ordinary feature blacklisting due to known bugs.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

arch/x86/kernel/cpu/common.c

@@ -570,8 +570,6 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
 	if (this_cpu->c_early_init)
 		this_cpu->c_early_init(c);
 
-	validate_pat_support(c);
-
 #ifdef CONFIG_SMP
 	c->cpu_index = boot_cpu_id;
 #endif