This patch removes the former use of ram_fs, fs_rom, and fs_report from
the subsystem and uses a report_rom instead. The fs-based reporting was
introduced to accommodate automatically instantiated usb_block drivers,
which turned out to be impractical for the sculpt scenario.
This is a drivers subsystem that starts the most fundamental
(framebuffer, input, block) device drivers dynamically, depending on the
runtime-detected devices. The discovered block devices are reported
as a "block_devices" report.
