Fix path to boot.mk after move

Change-Id: Idb91562e631425bde9ddc339c9fdd4e2aa6dd1b3
diff --git a/sdcard.mk b/sdcard.mk
index aaa1d4c..4e40597 100644
--- a/sdcard.mk
+++ b/sdcard.mk
@@ -31,7 +31,7 @@
 sdcard-xz: $(SDCARD_PATH).xz
 
 $(SDCARD_PATH): $(ROOTDIR)/build/rootfs.mk \
-                $(ROOTDIR)/build/boot.mk \
+                $(ROOTDIR)/board/boot.mk \
                 $(ROOTDIR)/board/fstab.sdcard \
                 | $(PRODUCT_OUT)/u-boot.imx \
                 $(PRODUCT_OUT)/boot_$(USERSPACE_ARCH).img \