Split SPD Connector to SDRAM fields, add unit tests

Change-Id: Ifaa79b70368c41789a199db78de2fa4e40768922
Reviewed-on: http://ralgit01.raleigh.ibm.com/gerrit1/46217
Tested-by: Jenkins Server <pfd-jenkins+hostboot@us.ibm.com>
Tested-by: Hostboot CI <hostboot-ci+hostboot@us.ibm.com>
Tested-by: FSP CI Jenkins <fsp-CI-jenkins+hostboot@us.ibm.com>
Reviewed-by: Louis Stermole <stermole@us.ibm.com>
Reviewed-by: STEPHEN GLANCY <sglancy@us.ibm.com>
Reviewed-by: JACOB L. HARVEY <jlharvey@us.ibm.com>
Reviewed-by: Jennifer A. Stofer <stofer@us.ibm.com>
Reviewed-on: http://ralgit01.raleigh.ibm.com/gerrit1/46224
Tested-by: Jenkins OP Build CI <op-jenkins+hostboot@us.ibm.com>
Tested-by: Jenkins OP HW <op-hw-jenkins+hostboot@us.ibm.com>
Reviewed-by: Christian R. Geddes <crgeddes@us.ibm.com>