thermal: intel: powerclamp: Do not log an error on unsupported CPUs

powerclamp_probe() returns -ENODEV unless x86_match_cpu() finds an
Intel CPU with MWAIT, and logs "CPU does not support MWAIT" at KERN_ERR
when it does not.

As a result, a kernel with CONFIG_INTEL_POWERCLAMP=y logs this error on
every boot on a non-Intel CPU.

  # grep -m1 vendor_id /proc/cpuinfo
  vendor_id	: AuthenticAMD
  # grep -m1 -o -w monitor /proc/cpuinfo
  monitor
  # dmesg -l err | grep intel_powerclamp:
  [    0.485728] intel_powerclamp: CPU does not support MWAIT

At KERN_ERR the line also gets past "quiet" and lands on the console,
and on kernel metrics.

Reduce it to debug, and also name both conditions in the message.

Signed-off-by: Breno Leitao <leitao@debian.org>
[ rjw: Rephrased the debug message ]
Link: https://patch.msgid.link/20261110-powerclamp_mwait_msg-v1-1-18c03fa17ebe@debian.org
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>