doc: imx: psb: Fix missing setexpr arguments

Due to copy-paste error, two of the setexpr arguments were missing.
Add the missing arguments.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Ye Li <ye.li@nxp.com>
Cc: uboot-imx <uboot-imx@nxp.com>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
1 file changed