regulator: Fix build breakage on !REGULATOR

Add missing stubs for regulator_suspend_prepare() and
regulator_suspend_finish() to fix exynos_defconfig build without
REGULATOR:

arch/arm/mach-exynos/built-in.o: In function `exynos_suspend_finish':
arch/arm/mach-exynos/suspend.c:537: undefined reference to `regulator_suspend_finish'
arch/arm/mach-exynos/built-in.o: In function `exynos_suspend_prepare':
arch/arm/mach-exynos/suspend.c:520: undefined reference to `regulator_suspend_prepare'
make: *** [vmlinux] Error 1

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Reported-by: Joerg Roedel <joro@8bytes.org>
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

include/linux/regulator/machine.h

@@ -191,15 +191,22 @@ struct regulator_init_data {
 	void *driver_data;	/* core does not touch this */
 };
 
-int regulator_suspend_prepare(suspend_state_t state);
-int regulator_suspend_finish(void);
-
 #ifdef CONFIG_REGULATOR
 void regulator_has_full_constraints(void);
+int regulator_suspend_prepare(suspend_state_t state);
+int regulator_suspend_finish(void);
 #else
 static inline void regulator_has_full_constraints(void)
 {
 }
+static inline int regulator_suspend_prepare(suspend_state_t state)
+{
+	return 0;
+}
+static inline int regulator_suspend_finish(void)
+{
+	return 0;
+}
 #endif
 
 #endif