util/board_status/board_status.sh: Save ROM contents in `cbfs.txt`

util/board_status/board_status.sh: Save ROM contents in `cbfs.txt`

The ROM content (CBFS content) captured with

	cbfstool build/coreboot.rom print

is useful for two reasons.

1. With the used configuration for the build in `.config`, it can be
compared how the size for romstage and ramstage change over time. To
make that reproducible the used toolchain should also be stored
somewhere in the future.

2. With the CBFS content the time stamps can be better interpreted.
For example, the size of the payload file is needed to interpret the
time stamp for loading the payload.

Change-Id: If77ca6412b1710e560f405f9a48df613c1819d36
Signed-off-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-on: http://review.coreboot.org/5867
Tested-by: build bot (Jenkins)
Reviewed-by: David Hendricks <dhendrix@chromium.org>
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-by: Marc Jones <marc.jones@se-eng.com>