board: traverse: ten64: update DPAA2 (network) binary path on sdcards

board: traverse: ten64: update DPAA2 (network) binary path on sdcards

Change the firmware on microSD path to "firmware/traverse/ten64"
as per EBBR section 4.2[1].

The Traverse firmware tools now locate the DPAA2 firmware
and configuration files under that path on the rescue
SD card image.
If a user then installs a standard Linux
distribution over the top of that sdcard, (in theory)
it will be left alone by distribution boot tooling.

Signed-off-by: Mathew McBride <matt@traverse.com.au>
[1] https://arm-software.github.io/ebbr/index.html#firmware-partition-filesystem

Reviewed-by: Peng Fan <peng.fan@nxp.com>