build: fix dependency of kernel_menuconfig target

When running "make kernel_menuconfig" in a clean tree, it fails with:

    make[1]: *** No rule to make target 'tools/quilt/install'.  Stop.

Replacing the dependency with 'tools/quilt/compile' fixes the issue (quilt
and all its prerequisites will be built, and quilt will be installed in
staging_dir).

Signed-off-by: Baptiste Jonglez <git@bitsofnetworks.org>

include/toplevel.mk

@@ -132,7 +132,7 @@ prepare_kernel_conf: .config FORCE
 
 ifeq ($(wildcard staging_dir/host/bin/quilt),)
   prepare_kernel_conf:
-	@+$(SUBMAKE) -r tools/quilt/install
+	@+$(SUBMAKE) -r tools/quilt/compile
 else
   prepare_kernel_conf: ;
 endif