scripts: import bin2c.c from Linux 4.10-rc6

Import scripts/basic/bin2c.c of Linux.

In Linux Kernel, this file was moved to scripts/basic directory by
commit 8370edea81e3 ("bin2c: move bin2c in scripts/basic").

In U-Boot, we do not need to follow that commit. Just put it in the
original directory "scripts".

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Simon Glass <sjg@chromium.org>