Fix 'make kernelconfig'

Using KERNEL_MAKE variable in this spot breaks things, for some reason
linking fails if KERNEL_MAKE_ENV is passed to make. Before, this worked
by accident because due to missing kernel-vars.mk include,
KERNEL_MAKE_ENV evaluated empty.

Fixes: e48e15bff4252 ("mk: Introduce KERNEL_MAKE variable")
Signed-off-by: Phil Sutter <phil@nwl.cc>

mk/build.mk

@@ -234,7 +234,9 @@ targethelp:
 	$(MAKE) -C target targethelp 
 
 kernelconfig:
-	${KERNEL_MAKE} menuconfig
+	${MAKE} -C "${LINUX_DIR}" \
+		ARCH=$(ADK_TARGET_KARCH) \
+		menuconfig
 
 ifeq ($(ADK_TARGET_LINUX_KERNEL_USE_CUSTOMCONFIG),y)
 savekconfig: