ARM: dts: imx: Add memory node unit name

Fix the following warnings from dtc by adding the unit name to memory
nodes:

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

Converted using the following command:

perl -p0777i -e 's/memory \{\n\t\treg = \<0x+([0-9a-f])/memory\@$1$\0000000 \{\n\t\treg = <0x$1/m' `find ./arch/arm/boot/dts -name "imx*"`

The files below were manually fixed:
-imx1-ads.dts
-imx1-apf9328.dts
-imx6q-pistachio.dts

Signed-off-by: Marco Franchi <marco.franchi@nxp.com>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>