linux-imx

ARM: at91/at91_dt_defconfig: remove memory specification to cmdline

No need for this cmdline option as we are using DT.
Moreover this defconfig is targeted to multiple SoC/boards: this option
was nonsense.

Reported-by: Josh Wu <josh.wu@atmel.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>