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 <[email protected]>
Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/
Signed-off-by: Viresh Kumar <[email protected]>
Link: https://patch.msgid.link/455e18c947bd9529701a2f1c796f0f934d1354d7.1738050679.git.viresh.kumar@linaro.org
Signed-off-by: Rafael J. Wysocki <[email protected]>

Author: vireshk

drivers/cpufreq/Kconfig.arm

@@ -17,7 +17,7 @@ config ARM_ALLWINNER_SUN50I_CPUFREQ_NVMEM
 
 config ARM_AIROHA_SOC_CPUFREQ
 	tristate "Airoha EN7581 SoC CPUFreq support"
-	depends on ARCH_AIROHA || COMPILE_TEST
+	depends on (ARCH_AIROHA && OF) || COMPILE_TEST
 	select PM_OPP
 	default ARCH_AIROHA
 	help