cpu/x86/mtrr/mtrr.c: Remove superfluous assignment to `type_index`

When building coreboot with the Clang static analyzer scan-build,
it reports »Value stored to 'type_index' is never read«. Indeed,
in `memranges_each_entry()` `type_index` is assigned a value
before being read. So remove that line.

Change-Id: I6da2fb8be7157bb98c57281babd4a08ca0d9f7a7
Signed-off-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-on: http://review.coreboot.org/3953
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@google.com>

src/cpu/x86/mtrr/mtrr.c

@@ -261,7 +261,6 @@ static void calc_fixed_mtrrs(void)
 
 	desc = &fixed_mtrr_desc[0];
 	last_desc = &fixed_mtrr_desc[ARRAY_SIZE(fixed_mtrr_desc) - 1];
-	type_index = desc->range_index;
 
 	memranges_each_entry(r, phys_addr_space) {
 		begin = range_entry_base_mtrr_addr(r);