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/include/asm/pat.h

@@ -5,10 +5,8 @@
 
 #ifdef CONFIG_X86_PAT
 extern int pat_enabled;
-extern void validate_pat_support(struct cpuinfo_x86 *c);
 #else
 static const int pat_enabled;
-static inline void validate_pat_support(struct cpuinfo_x86 *c) { }
 #endif
 
 extern void pat_init(void);
@@ -17,6 +15,4 @@ extern int reserve_memtype(u64 start, u64 end,
 		unsigned long req_type, unsigned long *ret_type);
 extern int free_memtype(u64 start, u64 end);
 
-extern void pat_disable(char *reason);
-
 #endif /* _ASM_X86_PAT_H */