PM / devfreq: Disable Exynos4 driver build on multiplatform

Exynos4 devfreq driver uses mach/map.h which is not available on
multiplatform. Hence disable build on multiplatform for now.
Without this patch we get the following build errors:
drivers/devfreq/exynos/exynos4_bus.h:15:22: fatal error: mach/map.h: No such file or directory
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/devfreq/Kconfig

@@ -67,7 +67,7 @@ comment "DEVFREQ Drivers"
 
 config ARM_EXYNOS4_BUS_DEVFREQ
 	bool "ARM Exynos4210/4212/4412 Memory Bus DEVFREQ Driver"
-	depends on CPU_EXYNOS4210 || SOC_EXYNOS4212 || SOC_EXYNOS4412
+	depends on (CPU_EXYNOS4210 || SOC_EXYNOS4212 || SOC_EXYNOS4412) && !ARCH_MULTIPLATFORM
 	select ARCH_HAS_OPP
 	select DEVFREQ_GOV_SIMPLE_ONDEMAND
 	help