arch: qemu-rv: Fix high CPU usage in SMP mode

[masayuki2009]

Summary

• I noticed that QEMU shows high CPU usage if the number of
  CPUs does not match the kernel configuration. (e.g. -smp 8
  and CONFIG_SMP_NCPUS=2)
• This commit fixes this issue.

Impact

• qemu-rv only

Testing

• Tested with the following configs
  • rv-virt:smp64 (CONFIG_NCPUS=1/2/8)
  • rv-virt:nsh64

[masayuki2009]

Hmm, what happened with the CI?

Successfully created virtual environment!
Virtualenv location: /home/runner/.local/share/virtualenvs/Documentation-IPZhXGF9
Installing dependencies from Pipfile.lock (d73b9c)...
To activate this project's virtualenv, run pipenv shell.
Alternatively, run a command inside the virtualenv with pipenv run.
Running Sphinx v3.5.3

Extension error:
Could not import extension sphinx.transforms.post_transforms.code (exception: No module named 'packaging')
make: *** [Makefile:45: html] Error 2
Error: Process completed with exit code 2.

[pkarashchenko]

@masayuki2009 I tried to restart CI multiple times, but the error persists

[pkarashchenko]

Let's ignore the error and see if the build pass on mainline

[pkarashchenko]

Seems that the same error persists. @xiaoxiang781216 @jerpelea do you know what can be the reason?