layerscape: add armv7 subtarget and ls1021atwr board support

The NXP TWR-LS1021A module is a development system based
on the QorIQ LS1021A processor.
- This feature-rich, high-performance processor module can
  be used standalone or as part of an assembled Tower System
  development platform.
- Incorporating dual Arm Cortex-A7 cores running up to 1 GHz,
  the TWR-LS1021A delivers an outstanding level of performance.
- The TWR-LS1021A offers HDMI, SATA3 and USB3 connectors as
  well as a complete Linux software developer's package.
- The module provides a comprehensive level of security that
  includes support for secure boot, Trust Architecture and
  tamper detection in both standby and active power modes,
  safeguarding the device from manufacture to deployment.

Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>

target/linux/layerscape/image/Makefile

@@ -43,4 +43,8 @@ ifeq ($(SUBTARGET),armv8_32b)
 include armv8_32b.mk
 endif
 
+ifeq ($(SUBTARGET),armv7)
+include armv7.mk
+endif
+
 $(eval $(call BuildImage))

target/linux/layerscape/image/armv7.mk

@@ -0,0 +1,31 @@
+#
+# Copyright 2018 NXP
+#
+# This is free software, licensed under the GNU General Public License v2.
+# See /LICENSE for more information.
+#
+
+define Device/Default
+  PROFILES := Default
+  FILESYSTEMS := squashfs
+  IMAGES := firmware.bin
+  KERNEL := kernel-bin | uImage none
+  KERNEL_NAME := zImage
+  KERNEL_LOADADDR := 0x80008000
+  KERNEL_ENTRY_POINT := 0x80008000
+endef
+
+define Device/ls1021atwr
+  DEVICE_TITLE := LS1021ATWR
+  DEVICE_PACKAGES += layerscape-rcw-ls1021atwr
+  DEVICE_DTS := ls1021a-twr
+  IMAGE/firmware.bin := \
+    ls-clean | \
+    ls-append $(1)-rcw.bin | pad-to 1M | \
+    ls-append $(1)-uboot.bin | pad-to 3M | \
+    ls-append $(1)-uboot-env.bin | pad-to 15M | \
+    ls-append-dtb $$(DEVICE_DTS) | pad-to 16M | \
+    append-kernel | pad-to 32M | \
+    append-rootfs | pad-rootfs | check-size 67108865
+endef
+TARGET_DEVICES += ls1021atwr