arm64: dts: lx2160a: Increase configuration space size

lx2160a rev2 requires 4KB space for type0 and 4KB
space for type1 iATU window. Increase configuration
space size to 8KB to have sufficient space for type0
and type1 window.

Signed-off-by: Wasim Khan <wasim.khan@nxp.com>
Reviewed-by: Li Yang <leoyang.li@nxp.com>
Acked-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>