Build p9_mcs_scom and p9_mcbist_scom in istep13
Build p9_mcs_scom and p9_mcbist_scom in istep13

These changes are required for change 25099 to pass HB CI file
changes will follow this commit that use these .o's so we need
to modify the make to build them.

Change-Id: I0e78e19282ea2d0dd163d9f88a2c7651c427c8d1
Reviewed-on: http://ralgit01.raleigh.ibm.com/gerrit1/25368
Tested-by: Jenkins Server
Reviewed-by: Matt Derksen <dfaaf609b81bd1529ae3a1d95ea4eeed3f78c848@us.ibm.com>
Tested-by: FSP CI Jenkins
Reviewed-by: Andres A. Lugo-Reyes <1e80b37233adece4fe8991e4578aec38a057d106@us.ibm.com>
Reviewed-by: Daniel M. Crowell <912029ca9254ac7b5854e56910561d682e1fa2d0@us.ibm.com>

open-power/hostboot,open-power/hostboot,open-power/hostboot,open-power/hostboot,open-power/hostboot