Semi-trivial: split build configs for ES1 into workram and spirom
Semi-trivial: split build configs for ES1 into workram and spirom

See title.

Testing Done: Attempt to bring up BDB1B-APB2 with bootrom, encountered the bug fixed by #795
Bug Number:
Review URL: https://reviews.leaflabs.com/r/793
Reviewed by: Marti Bolivar, Jun Li

gregkh/bootrom,projectara/bootrom