Fix sdcard partition execution

- Eh, this shouldn't be in $(shell), that executes it when everything
expands it, which is clearly wrong. Just run it normally instead.

Change-Id: Ie7ed95161727e0dde3ab7e40e41e977bcf19554b
diff --git a/sdcard.mk b/sdcard.mk
index 63d80f8..aaa1d4c 100644
--- a/sdcard.mk
+++ b/sdcard.mk
@@ -49,7 +49,7 @@
 	mkdir -p $(ROOTFS_DIR)
 	-sudo umount $(ROOTFS_DIR)/boot
 	-sudo umount $(ROOTFS_DIR)
-	$(shell $(ROOTDIR)/board/make_sdcard.sh $(ROOTFS_DIR) $(SDCARD_WIP_PATH) $(ROOTDIR))
+	$(ROOTDIR)/board/make_sdcard.sh $(ROOTFS_DIR) $(SDCARD_WIP_PATH) $(ROOTDIR)
 	rmdir $(ROOTFS_DIR)
 
 	mv $(SDCARD_WIP_PATH) $(SDCARD_PATH)