Use puts() because printf() isn't necessary,
to fix the following compiler warnings:

/barebox/common/menu.c: In function ‘menu_show’:
/barebox/common/menu.c:277:4: warning: format not a string literal and no format arguments [-Wformat-security]

/barebox/scripts/omap4_usbboot.c: In function ‘read_asic_id’:
/barebox/scripts/omap4_usbboot.c:101:3: warning: format not a string literal and no format arguments [-Wformat-security]

Signed-off-by: Fabio Porcedda <fabio.porcedda@gmail.com>
Cc: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Cc: Vicente <vicencb@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>