Useful rules in scripts/Makefile.lib allows us to easily
generate a device tree blob and wrap it in assembly code.
We do not need to parse a linker script to get output format and arch.
This commit deletes ./u-boot.dtb since it is a copy of dts/dt.dtb.
Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
