Game Driver: update the format of driver build date

This change updates the original string base driver build date to
int64_t based driver build time. The build time is the Unix epoch
timestamp.

Bug: 123156461
Test: Build, flash and boot. Verify the GpuService receiver side.
Change-Id: Ia9e0c64c5dfa6f4bb84a0c05e982b481079158a7
diff --git a/services/gpuservice/GpuService.h b/services/gpuservice/GpuService.h
index 76234a3..389e695 100644
--- a/services/gpuservice/GpuService.h
+++ b/services/gpuservice/GpuService.h
@@ -38,7 +38,7 @@
 private:
     // IGpuService interface
     void setGpuStats(const std::string& driverPackageName, const std::string& driverVersionName,
-                     uint64_t driverVersionCode, const std::string& driverBuildDate,
+                     uint64_t driverVersionCode, int64_t driverBuildTime,
                      const std::string& appPackageName, GraphicsEnv::Driver driver,
                      bool isDriverLoaded, int64_t driverLoadingTime);