kernel: Remove kernel{x}config

* They haven't been working since ninja build was introduced

Change-Id: Icb51412b7a70cdec7f077a6d3d56f7720188bcb0
diff --git a/build/tasks/kernel.mk b/build/tasks/kernel.mk
index 61d63bc..7a674ee 100644
--- a/build/tasks/kernel.mk
+++ b/build/tasks/kernel.mk
@@ -251,18 +251,7 @@
 	$(hide) mkdir -p $(KERNEL_OUT)
 	$(MAKE) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) $(KERNEL_CLANG_TRIPLE) $(KERNEL_CC) tags
 
-.PHONY: kernelconfig kernelxconfig kernelsavedefconfig alldefconfig
-
-kernelconfig:  KERNELCONFIG_MODE := menuconfig
-kernelxconfig: KERNELCONFIG_MODE := xconfig
-kernelxconfig kernelconfig:
-	$(hide) mkdir -p $(KERNEL_OUT)
-	$(MAKE) $(KERNEL_MAKE_FLAGS) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) $(KERNEL_CLANG_TRIPLE) $(KERNEL_CC) $(KERNEL_DEFCONFIG)
-	env KCONFIG_NOTIMESTAMP=true \
-		 $(MAKE) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) $(KERNEL_CLANG_TRIPLE) $(KERNEL_CC) $(KERNELCONFIG_MODE)
-	env KCONFIG_NOTIMESTAMP=true \
-		 $(MAKE) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) $(KERNEL_CLANG_TRIPLE) $(KERNEL_CC) savedefconfig
-	cp $(KERNEL_OUT)/defconfig $(KERNEL_DEFCONFIG_SRC)
+.PHONY: kernelsavedefconfig alldefconfig
 
 kernelsavedefconfig:
 	$(hide) mkdir -p $(KERNEL_OUT)