use uImage kernel format for kinetis-k70

target/arm/kernel/kinetis-k70

@@ -19,3 +19,4 @@ CONFIG_GPIOLIB=y
 CONFIG_SLAB=y
 CONFIG_SERIAL_KINETIS=y
 CONFIG_SERIAL_KINETIS_CONSOLE=y
+CONFIG_CMDLINE=console=ttyS2,115200 rw root=/dev/nfs ip=dhcp kinetis_platform=k70-som"

target/arm/systems/kinetis-k70

@@ -11,7 +11,8 @@ config ADK_TARGET_SYSTEM_KINETIS_K70
 	select ADK_TARGET_WITH_BLOCK
 	select ADK_TARGET_WITH_NAND
 	select ADK_TARGET_UCLINUX
-	select ADK_TARGET_KERNEL_IMAGE
+	select ADK_TARGET_KERNEL_UIMAGE
+	select ADK_HOST_BUILD_U_BOOT
 	help
 	  Kinetis K70