board: traverse: ten64: specify bootargs for recovery environment

board: traverse: ten64: specify bootargs for recovery environment

The recovery environment[1] on the Ten64 is a OpenWrt-
based ramdisk stored on the NAND intended to help with
system setup tasks.

Before the bootargs were not being set for the recovery
command, relying instead on the existing bootargs variable.

Ensure the bootargs are set correctly prior to booting recovery.

Signed-off-by: Mathew McBride <matt@traverse.com.au>
[1] https://ten64doc.traverse.com.au/software/recovery/

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