arm64: dts: ls1012a: add the DTS node for DSPI support

Signed-off-by: Yuan Yao <yao.yuan@nxp.com>
Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>