arm64: dts: imx8dxl: add flexspi0 support

Add flexspi0 node at common lsio subsystem.
Change flexspi0 irq number for imx8dxl.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>