mainboard/intel/minnowmax: use Baytrail Gold3 FSP

Baytrail Gold3 FSP support memory down configuration.  Update Minnow Max
to use Gold3 FSP.  Set memory down data in devicetree.cb, instead of use
different FSP image.

Change-Id: Ic03da2d2a1cee5144b9a013d3dd9f982ff043123
Signed-off-by: York Yang <york.yang@intel.com>
Reviewed-on: http://review.coreboot.org/7581
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
Reviewed-by: Martin Roth <gaumless@gmail.com>
vendorcode/intel/fsp: Update FSP_VENDORCODE_HEADER_PATH

Minor change in Kconfig to remove "/" defined in
FSP_VENDORCODE_HEADER_PATH and update the path in Makefile.inc.

Change-Id: Ic19ab9560aabe307d45b560f167874383cc920aa
Signed-off-by: Fei Wang <wangfei.jimei@gmail.com>
Signed-off-by: FEI WANG <wangfei.jimei@gmail.com>
Reviewed-on: http://review.coreboot.org/5894
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <gaumless@gmail.com>
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>