kernel: Drop 'kernel_' prefix from kernel config files

It's kinda obvious that these are kernel configuration files
and, looking at various other distros it seems more common
to call the files 'config-<foo>'.

Signed-off-by: Rolf Neugebauer <rolf.neugebauer@docker.com>

kernel/Dockerfile

@@ -78,13 +78,13 @@ RUN case $(uname -m) in \
         KERNEL_DEF_CONF=/linux/arch/arm64/configs/defconfig; \
         ;; \
     esac  && \
-    cp /kernel_config-${KERNEL_SERIES}-$(uname -m) ${KERNEL_DEF_CONF}; \
+    cp /config-${KERNEL_SERIES}-$(uname -m) ${KERNEL_DEF_CONF}; \
     if [ -n "${EXTRA}" ]; then \
         sed -i "s/CONFIG_LOCALVERSION=\"-linuxkit\"/CONFIG_LOCALVERSION=\"-linuxkit${EXTRA}\"/" ${KERNEL_DEF_CONF}; \
         if [ "${EXTRA}" = "-dbg" ]; then \
             sed -i 's/CONFIG_PANIC_ON_OOPS=y/# CONFIG_PANIC_ON_OOPS is not set/' ${KERNEL_DEF_CONF}; \
         fi && \
-        cat /kernel_config${EXTRA} >> ${KERNEL_DEF_CONF}; \
+        cat /config${EXTRA} >> ${KERNEL_DEF_CONF}; \
     fi && \
     make defconfig && \
     make oldconfig && \

kernel/Dockerfile.kconfig

@@ -32,8 +32,8 @@ RUN for VERSION in ${KERNEL_VERSIONS}; do \
                    patch -p1 < "$patch"; \
                done; \
             fi && \
-        mv /kernel_config-${SERIES}-x86_64 arch/x86/configs/x86_64_defconfig && \
-        mv /kernel_config-${SERIES}-aarch64 arch/arm64/configs/defconfig; \
+        mv /config-${SERIES}-x86_64 arch/x86/configs/x86_64_defconfig && \
+        mv /config-${SERIES}-aarch64 arch/arm64/configs/defconfig; \
     done
 
 ENTRYPOINT ["/bin/sh"]

kernel/Makefile

@@ -19,7 +19,7 @@ IMAGE_PERF:=kernel-perf
 IMAGE_ZFS:=zfs-kmod
 
 # You can specify an extra options for the Makefile. This will:
-# - append a kernel_config$(EXTRA) to the kernel config for your kernel/arch
+# - append a config$(EXTRA) to the kernel config for your kernel/arch
 # - append $(EXTRA) to the CONFIG_LOCALVERSION of your kernel
 EXTRA?=
 
@@ -93,7 +93,7 @@ sources/linux-$(1).tar.xz: Makefile | sources
 KERNEL_VERSIONS+=$(1)
 endif
 
-build_$(2)$(3): Dockerfile Makefile $(wildcard patches-$(2)/*) $(wildcard kernel_config-$(2)*) kernel_config-dbg | sources
+build_$(2)$(3): Dockerfile Makefile $(wildcard patches-$(2)/*) $(wildcard config-$(2)*) config-dbg | sources
 	docker pull $(ORG)/$(IMAGE):$(1)$(3)-$(TAG)$(SUFFIX) || \
 		docker build \
 			--build-arg KERNEL_VERSION=$(1) \