imx6_bbu_nand_register_handler is dependent on
CONFIG_BAREBOX_UPDATE_IMX6_NAND. Change the protoype definition such
that said function is stubbed-out when CONFIG_BAREBOX_UPDATE_IMX6_NAND
is not defined.
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>