ARM: exynos: Correct the help text for platform Kconfig option

ARCH_EXYNOS option is used for entire ARMv7 Exynos family, including
also Exynos3 SoCs.
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

arch/arm/mach-exynos/Kconfig

@@ -41,7 +41,7 @@ menuconfig ARCH_EXYNOS
 	select POWER_RESET_SYSCON
 	select POWER_RESET_SYSCON_POWEROFF
 	help
-	  Support for SAMSUNG EXYNOS SoCs (EXYNOS4/5)
+	  Support for SAMSUNG EXYNOS SoCs
 
 if ARCH_EXYNOS