arm64: dts: freescale: imx8qxp: Fix the keys node name

The proper name is 'keys', not 'scu-keys'.

Signed-off-by: Abel Vesa <abel.vesa@nxp.com>
Signed-off-by: Viorel Suman <viorel.suman@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>