soc: samsung: chipid: Select missing dependency for EXYNOS_CHIPID

The chipid driver uses the MFD syscon API but it was not covered
properly in Kconfig.
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

drivers/soc/samsung/Kconfig

@@ -10,6 +10,7 @@ if SOC_SAMSUNG
 config EXYNOS_CHIPID
 	bool "Exynos Chipid controller driver" if COMPILE_TEST
 	depends on ARCH_EXYNOS || COMPILE_TEST
+	select MFD_SYSCON
 	select SOC_BUS
 
 config EXYNOS_PMU