lx2160ardb: define RCWEMMC
EMMC boot on LX2160A RDB is supported now. Define RCWEMMC for atf
build.
Documents:
What's New in LSDK 20.04:
https://docs.nxp.com/bundle/GUID-
51EEFEDB-ABD5-40C0-BEBD-
6527B3494D57/page/GUID-
01DD18F7-27DC-4A0F-B79B-
FBB5CBA5F4C0.html
LX2160A Reference Design Board:
https://www.nxp.com/design/qoriq-developer-resources/layerscape-lx2160a-reference-design-board:LX2160A-RDB
LX2160A Multicore Communications Processor:
https://www.nxp.com/products/processors-and-microcontrollers/arm-processors/layerscape-communication-process/layerscape-lx2160a-multicore-communications-processor:LX2160A
Signed-off-by: Ting Liu <ting.liu@nxp.com>
