Generate an autoscript for configuring u-boot in $(BINARIES_DIR)

mkimage the autoscript to autoscript.$(PROJECT)-
Move build of u-boot-1.2.0-atmel to target/u-boot
	Only visible for AT91 targets.
Fetch prepatched 1.2.0-atmel tarball from $(BR2_ATMEL_MIRROR)
Rest from normal location.
Introduce U_BOOT_CONFIGURE_OPTS
	Set to NOSOFT_FLOAT for u-boot-1.2.0-atmel
Disable target/device/Atmel/u-boot
Keep files in target/device/Atmel/u-boot during a test period.

Files:
M      target/device/Atmel/Makefile.in
M      target/device/Atmel/Config.in
M      target/u-boot/Makefile.in
M      target/u-boot/Config.in
A      target/u-boot/1.2.0-atmel