thermal/intel: Fix intel_tcc_get_temp() to support negative CPU temperature

CPU temperature can be negative in some cases. Thus the negative CPU
temperature should not be considered as a failure.

Fix intel_tcc_get_temp() and its users to support negative CPU
temperature.

Fixes: a3c1f066 ("thermal/intel: Introduce Intel TCC library")
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
Cc: 6.3+ <stable@vger.kernel.org> # 6.3+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>