Users may disable HWP in firmware, in which case intel_pstate will give up
unless the CPU model is explicitly supported.

See also the following past commits:

 - commit df51f287 ("cpufreq: intel_pstate: Add Sapphire Rapids support
   in no-HWP mode")
 - commit d8de7a44 ("cpufreq: intel_pstate: Add Skylake servers support")
 - commit 706c5328 ("cpufreq: intel_pstate: Add Cometlake support in
   no-HWP mode")
 - commit fbdc21e9 ("cpufreq: intel_pstate: Add Icelake servers support in
   no-HWP mode")
 - commit 71bb5c82 ("cpufreq: intel_pstate: Add Tigerlake support in
   no-HWP mode")
Signed-off-by: Zhenguo Yao <yaozhenguo1@gmail.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
[ rjw: Changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>