[risc-v][common64] Make rt_hw_cpu_shutdown weak to resolve multiple definition with RT_USING_DM#11100

Rbb666 merged 2 commits intomasterRT-Thread/rt-thread:masterfrom

copilot/fix-rt-hw-cpu-shutdown-errorRT-Thread/rt-thread:copilot/fix-rt-hw-cpu-shutdown-errorCopy head branch name to clipboard