rtc: sun6i: Disable the build as a module

Since we have to provide the clock very early on, the RTC driver cannot be
built as a module. Make sure that won't happen.

Cc: stable@vger.kernel.org
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

drivers/rtc/Kconfig

@@ -1434,7 +1434,7 @@ config RTC_DRV_SUN4V
 	  based RTC on SUN4V systems.
 
 config RTC_DRV_SUN6I
-	tristate "Allwinner A31 RTC"
+	bool "Allwinner A31 RTC"
 	default MACH_SUN6I || MACH_SUN8I || COMPILE_TEST
 	depends on ARCH_SUNXI
 	help

drivers/rtc/rtc-sun6i.c

@@ -439,9 +439,4 @@ static struct platform_driver sun6i_rtc_driver = {
 		.of_match_table = sun6i_rtc_dt_ids,
 	},
 };
-
-module_platform_driver(sun6i_rtc_driver);
-
-MODULE_DESCRIPTION("sun6i RTC driver");
-MODULE_AUTHOR("Chen-Yu Tsai <wens@csie.org>");
-MODULE_LICENSE("GPL");
+builtin_platform_driver(sun6i_rtc_driver);