armv8/fsl_lsch3: Change arch to fsl-layerscape

There are two LS series processors are built on ARMv8 Layersacpe
architecture currently, LS2085A and LS1043A. They are based on
ARMv8 core although use different chassis, so create fsl-layerscape
to refactor the common code for the LS series processors which also
paves the way for adding LS1043A platform.

Signed-off-by: Mingkai Hu <Mingkai.Hu@freescale.com>
Signed-off-by: Hou Zhiqiang <B48286@freescale.com>
Signed-off-by: Gong Qianyu <Qianyu.Gong@freescale.com>
Reviewed-by: York Sun <yorksun@freescale.com>