badblocks: add new test

Add a new test to run badblocks in read-only mode.

By default, the test will run on the block device where the
rootfs is mounted.

Callers can either set BADBLOCKS_DEVICE variable to test a different
device, or pass the "-d <device>" parameter into badblocks.sh

Additional parameters can also be passed by either setting the
BADBLOCKS_PARAMS variable or passing "-p <params>" to badblocks.sh.

For example, passing the additional parameter "-n" will ask badblocks to
run a read-write test. Note: this will fail is the block device is
mounted, eg. for the rootfs.

Change-Id: Ifa04d78cddb2070110cb7c6eb465f9364f281f6c
Signed-off-by: Ryan Harkin <ryan.harkin@linaro.org>
2 files changed