cpufreq: Make CONFIG_CPUFREQ_DT_PLATDEV depend on OF

The cpufreq-dt-platform.c driver requires CONFIG_OF to be selected. Mark
it as a dependency.
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202306250025.savpMM8L-lkp@intel.com/Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/Kconfig

@@ -219,6 +219,7 @@ config CPUFREQ_DT
 
 config CPUFREQ_DT_PLATDEV
 	tristate "Generic DT based cpufreq platdev driver"
+	depends on OF
 	help
 	  This adds a generic DT based cpufreq platdev driver for frequency
 	  management.  This creates a 'cpufreq-dt' platform device, on the