nb/intel/sandybridge/raminit: Make discover_timC_write non cyclic

The code can't handle cyclic zero runs. Make sure it will never
wrap around by setting the top-most bit to constant one.

Fixes "Mini channel test failed (2)".

Test system:
 * Gigabyte GA-B75M-D3H
 * Intel Pentium CPU G2130

Change-Id: I55e610d984d564bd4675f9318dead6d6c1e288a3
Signed-off-by: Patrick Rudolph <siro@das-labor.org>
Reviewed-on: https://review.coreboot.org/13853
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>
1 file changed