usb_host: Implement set_address()

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
libqiprog: Add core implementation for readn()/writen()

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
libqiprog: Style fixes (Trivial)

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>