Avoid false detection of SMSC FDC37N972 when Infineon TPM is present

Avoid false detection of SMSC FDC37N972 when Infineon TPM is present

Change-Id: Ibfb3af4c5d7675a5d4e27021cbb988c2ce00fd9f
Signed-off-by: Jonathan A. Kollasch <jakllsch@kollasch.net>
Reviewed-on: http://review.coreboot.org/420
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>