Barebox do not have support for MACH_NXDKN, MACH_NXHMIBB, MACH_NXEB500HMI and MACH_NXHX boards, so remove these symbols. Signed-off-by: Alexander Shiyan <shc_work@mail.ru> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>