mx51evk: add u-boot.imx to ALL target

Signed-off-by: Loic Minier <loic.minier@linaro.org>
CC: stefano babic <sbabic@denx.de>

board/freescale/mx51evk/config.mk

@@ -23,3 +23,4 @@
 LDSCRIPT = $(CPUDIR)/$(SOC)/u-boot.lds
 TEXT_BASE = 0x97800000
 IMX_CONFIG = $(SRCTREE)/board/$(BOARDDIR)/imximage.cfg
+ALL += $(obj)u-boot.imx