package/sunxi-tools: support all tools

This patch allows to select the installation of additional commands
which are part of the sunxi-tools. It's now possible to e.g. install
sunxi-fel on the target device. The corresponding options have been
added to Config.in and sunxi-tools.mk has been modified respectively.
The default setting is to only build sunxi-nand-part.

On the host building of the misc-tools target is added, which provides
sunxi-nand-image-builder and phoenix_info.

Signed-off-by: Alex Kaplan <kaplan2539@gmail.com>
[Thomas:
 - properly format Config.in
 - do not select BR2_PACKAGE_HOST_LIBUSB in Config.in.host, since this
   option doesn't exist
 - properly indent code in sunxi-tools.mk]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>