Fix mtune [skip ci]

Author: Claudio Raimondi

Dockerfile

@@ -140,7 +140,7 @@ ARG CXX=${target_arch}-g++
 ARG LD=${target_arch}-ld
 ARG STRIP=${target_arch}-strip
 ARG TARGET=${target_arch_rust}
-ARG COPTFLAGS="-O2 -march=${target_arch_cflags} -mtune=generic"
+ARG COPTFLAGS="-O2 -march=${target_arch_cflags}"
 
 WORKDIR /opt
 
@@ -161,7 +161,7 @@ EOF
 #TODO: maybe only compile lightningd? instead of all the plugins as well
 RUN ./configure --prefix=/opt/lightningd --enable-static --disable-compat --disable-valgrind
 COPY .git/ .git/
-RUN git submodule update --init --recursive
+RUN git submodule update --init --recursive --jobs $(nproc) --depth 1
 RUN uv run make -j$(nproc) install
 
 RUN ${STRIP} --strip-unneeded bin/lightningd