cros-build/firmware: Update dates in binary file names
During some of the previous Depthcharge and firmware image updates I forgot to update the date in the binary file names. Modify them to match the Depthcharge build date shown in the boot log.
Also, track the rammus firmware binary in cros-build instead of in cros-build/firmware.
Signed-off-by: Ricardo Cañuelo email@example.com