i386: mtrr crash fix

Commit 3ebad590

 ("[PATCH] x86: Save and
restore the fixed-range MTRRs of the BSP when suspending") added mtrr
operations without verifying that the CPU has MTRRs.  Crashes transmeta
CPUs.

Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: <linux@horizon.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>