Remove non-ascii & unprintable characters

These non-ascii & unprintable characters aren't needed.

Change-Id: I129f729f66d6a692de729d76971f7deb7a19c254
Signed-off-by: Martin Roth <martinroth@google.com>
Reviewed-on: https://review.coreboot.org/15977
Tested-by: build bot (Jenkins)
Reviewed-by: Omar Pakker
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/cpu/intel/slot_1/l2_cache.c

@@ -339,7 +339,7 @@ int test_l2_address_alias(u32 address1, u32 address2,
 
 /* Calculates the L2 cache size.
  *
- * Reference: Intel(R) 64 and IA-32 Architectures Software Developer<EFBFBD>s Manual
+ * Reference: Intel(R) 64 and IA-32 Architectures Software Developer's Manual
  *            Volume 3B: System Programming Guide, Part 2, Intel pub. 253669, pg. B-172.
  *
  */