amd/mct/ddr3: Allow critical delay delta to go negative

The critical delay delta was incorrectly specified as an
unsigned short.  Use a signed short instead.

Found-by: Coverity Scan #1347355
Change-Id: I37d769afb8c8af85a0375ae459e9d4ab0adcca74
Signed-off-by: Timothy Pearson <tpearson@raptorengineering.com>
Reviewed-on: https://review.coreboot.org/18071
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Tested-by: Raptor Engineering Automated Test Stand <noreply@raptorengineeringinc.com>
1 file changed