layerscape: add ls1012afrwy support and drop ls1012afrdm

layerscape: add ls1012afrwy support and drop ls1012afrdm

ls1012afrdm was no longer supported in NXP Layerscape SDK.
Instead a new board ls1012afrwy was introduced in LSDK.
This patch is to drop ls1012afrdm and add ls1012afrwy support.
Since only 2MB NOR flash could be used, we just put u-boot
and firmware on NOR flash, and put kernel/dtb/rootfs on SD
card.

The Layerscape FRWY-LS1012A board is an ultra-low-cost
development platform for LS1012A Series Communication
Processors built on Arm Cortex-A53. This tool refines the
FRDM-LS1012A with more features for a better hands-on experience
for IoT, edge computing, and various advanced embedded
applications. Features include easy access to processor I/O,
low-power operation, micro SD card storage, an M2 connector, a
small form factor, and expansion board options via mikroBUS Click
Module. The MicroBUS Module provides easy expansion via hundreds
of powerful modules supporting sensors, actuators, memories,
and displays.

Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>
(backported from 7016dd48f164364e1ee7b9d86169375691f7be0d)