mbv: clean up build

mbv/Dockerfile

@@ -1,3 +1,5 @@
+ARG TARGET
+
 FROM debian:bookworm AS deps
 
 RUN DEBIAN_FRONTEND=noninteractive apt-get update && \
@@ -9,27 +11,16 @@ RUN cd /opt && curl -L https://github.com/xpack-dev-tools/riscv-none-elf-gcc-xpa
 FROM deps AS dev
 
 
-FROM deps AS bootloader-build
+FROM deps AS build
+ARG TARGET=${TARGET}
 
 ADD . /workspace
 WORKDIR /workspace
 
-RUN make bootloader.bin
+RUN make ${TARGET}
 
 
-FROM deps AS app-build
+FROM scratch AS export
+ARG TARGET=${TARGET}
 
-ADD . /workspace
-WORKDIR /workspace
-
-RUN make app.bin
-
-
-FROM scratch AS bootloader-export
-
-COPY --from=bootloader-build /workspace/bootloader.bin /
-
-
-FROM scratch AS app-export
-
-COPY --from=app-build /workspace/app.bin /
+COPY --from=build /workspace/${TARGET} /