arm64: dts: imx8mp: Add src node interrupts

Interrupts is a required property according to SRC binding, add
it for SRC node.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Reviewed-by: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>