[Experiment] Try with GNU objdump

Author: sayantn

ci/docker/riscv64gc-unknown-linux-gnu/Dockerfile

@@ -10,4 +10,4 @@ ENV CARGO_TARGET_RISCV64GC_UNKNOWN_LINUX_GNU_LINKER=riscv64-linux-gnu-gcc \
       -L /usr/riscv64-linux-gnu \
       -cpu rv64,zk=true,zks=true,zbb=true,zbc=true \
     " \
-    OBJDUMP=llvm-objdump
+    OBJDUMP=riscv64-linux-gnu-objdump