at91dataflashboot: use "config" instead of "menuconfig"
Since at91dataflashboot has no suboption, using "menuconfig" is
useless and confusing, as it creates an empty submenu in the
configuration interface.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>