x86_64: Add asm/mtrr.h include for some builds

The earlier change to call the bp mtrr init from bugs.c broke
on some configurations due to missing includes.  Noticed
by "Avuton Olrich" <avuton@gmail.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/x86_64/kernel/bugs.c

@@ -9,6 +9,7 @@
 #include <linux/init.h>
 #include <asm/alternative.h>
 #include <asm/processor.h>
+#include <asm/mtrr.h>
 
 void __init check_bugs(void)
 {