drivers/cpuidle: make cpuidle-exynos.c explicitly non-modular

The Kconfig currently controlling compilation of this code is:

cpuidle/Kconfig.arm:config ARM_EXYNOS_CPUIDLE
cpuidle/Kconfig.arm:    bool "Cpu Idle Driver for the Exynos processors"

...meaning that it currently is not being built as a module by anyone.

Lets remove the couple traces of modularity so that when reading the
driver there is no doubt it is builtin-only.

Since module_platform_driver() uses the same init level priority as
builtin_platform_driver() the init ordering remains unchanged with
this commit.

Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpuidle/cpuidle-exynos.c

@@ -14,7 +14,7 @@
 #include <linux/cpuidle.h>
 #include <linux/cpu_pm.h>
 #include <linux/export.h>
-#include <linux/module.h>
+#include <linux/init.h>
 #include <linux/platform_device.h>
 #include <linux/of.h>
 #include <linux/platform_data/cpuidle-exynos.h>
@@ -142,5 +142,4 @@ static struct platform_driver exynos_cpuidle_driver = {
 		.name = "exynos_cpuidle",
 	},
 };
-
-module_platform_driver(exynos_cpuidle_driver);
+builtin_platform_driver(exynos_cpuidle_driver);