rust: rcpufreq_dt: add module alias

Add the missing `platform:cpufreq-dt` module alias so that the driver
can be automatically loaded when the platform device is registered.

Fixes: 06149d8f22 ("cpufreq: Add Rust-based cpufreq-dt driver")
Cc: stable@vger.kernel.org
Signed-off-by: Frank Zhang <rmxpzlb@gmail.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

drivers/cpufreq/rcpufreq_dt.rs

@@ -225,4 +225,5 @@ fn probe<'bound>(
     authors: ["Viresh Kumar <viresh.kumar@linaro.org>"],
     description: "Generic CPUFreq DT driver",
     license: "GPL v2",
+    alias: ["platform:cpufreq-dt"],
 }