arm: dts: ls1021a: Fix typo of MSI compatible string

"1" should be replaced by "l". This is a typo.
The patch is to fix it.

Signed-off-by: Minghuan Lian <Minghuan.Lian@nxp.com>
Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>