ARM: dts: bcm283x: Fix DTC warning for memory node

Compiling the bcm283x DTS with W=1 leads to the following warning:

Warning (unit_address_vs_reg): /memory: node has a reg or ranges property,
but no unit name

Fix this by adding the unit address.

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Tested-by: Peter Robinson <pbrobinson@gmail.com>
Reviewed-by: Eric Anholt <eric@anholt.net>