The following build warnings are seen with W=1:

Warning (unit_address_vs_reg): Node /display@di0 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /display@di1 has a unit name, but no reg property

Fix all these warnings by changing 'display@diX' to 'dispX'.
Signed-off-by: NMarco Franchi <marco.franchi@nxp.com>
Acked-by: NPhilipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: NFabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: NShawn Guo <shawnguo@kernel.org>