The patch fixes this sphinx warnings:
barebox/Documentation/user/usb.rst:61: WARNING: Could not lex literal_block as "c". Highlighting skipped.
Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
Cc: Robert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>