mb/biostar: Get rid of device_t

Use of device_t has been abandoned in ramstage.

Change-Id: Ifc9d82270513f4b4f34d9cf210c37029202b5a5f
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/26079
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Rudolph <siro@das-labor.org>
4 files changed