Fix a few edge cases with error handling in cpufreq(4)'s CPUFREQ_GET() method: - If the last of the child cpufreq drivers returns an error while trying to   fetch its list of supported frequencies but an earlier driver found the   requested frequency, don't return an error to the caller. - If all of the child cpufreq drivers fail and the attempt to match the   frequency based on 'cpu_est_clockrate()' fails, return ENXIO rather than   returning success and returning a frequency of CPUFREQ_VAL_UNKNOWN.
Fix a few edge cases with error handling in cpufreq(4)'s CPUFREQ_GET()
method:
- If the last of the child cpufreq drivers returns an error while trying to
  fetch its list of supported frequencies but an earlier driver found the
  requested frequency, don't return an error to the caller.
- If all of the child cpufreq drivers fail and the attempt to match the
  frequency based on 'cpu_est_clockrate()' fails, return ENXIO rather than
  returning success and returning a frequency of CPUFREQ_VAL_UNKNOWN.

MFC after:	3 days
PR:		kern/121433
Reported by:	Eugene Grosbein  eugen ! kuzbass dot ru

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase