dts/ls2080a: Update PCIe compatible

The patch adds LS2085a to PCIe compatible to fix the compatibility
issue when using firmware with LS2085a compatible property.

Signed-off-by: Minghuan Lian <minghuan.lian@nxp.com>
Signed-off-by: Mingkai Hu <mingkai.hu@nxp.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Olof Johansson <olof@lixom.net>