ARM: at91: dt: remove unit-address part for memory nodes

Because of the inclusion of skeleton.dtsi, the memory node is
named "memory" we where not modifying the already included one
but creating a new one. It caused bad memory node detection during
early_init_dt_scan_memory() so we modify them.

Signed-off-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Cc: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Cc: devicetree-discuss@lists.ozlabs.org