ARM: dts: imx28-m28evk: Fix display duplicate name warning

The lcdif node has a property named "display" and also a child node
called "display", which causes the following warning:

device-tree: Duplicate name in lcdif@80030000, renamed to "display#1"

Rename the child node name in order to avoid the warning.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@freescale.com>