uboot: remove now-redundant ccache handling

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Reviewed-by: Romain Naour <romain.naour@openwide.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

boot/uboot/uboot.mk

@@ -74,7 +74,7 @@ endif
 UBOOT_ARCH = $(KERNEL_ARCH)
 
 UBOOT_MAKE_OPTS += \
-	CROSS_COMPILE="$(CCACHE) $(TARGET_CROSS)" \
+	CROSS_COMPILE="$(TARGET_CROSS)" \
 	ARCH=$(UBOOT_ARCH)
 
 # Helper function to fill the U-Boot config.h file.