cpufreq: airoha: Depends on OF

cpufreq: airoha: Depends on OF

The Airoha cpufreq depends on OF and must be marked as such. With the
kernel compiled without OF support, we get following warning:

drivers/cpufreq/airoha-cpufreq.c:109:34: warning: 'airoha_cpufreq_match_list' defined but not used [-Wunused-const-variable=]
    109 | static const struct of_device_id airoha_cpufreq_match_list[] __initconst = {
        |                                  ^~~~~~~~~~~~~~~~~~~~~~~~~

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202501251941.0fXlcd1D-lkp@intel.com/
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://patch.msgid.link/455e18c947bd9529701a2f1c796f0f934d1354d7.1738050679.git.viresh.kumar@linaro.org
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>