staging: nvec: let nvec select MFD_CORE

NVEC registers a mfd device and therefore needs to select MFD_CORE.
Signed-off-by: Marc Dietrich <marvin24@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/nvec/Kconfig

 config MFD_NVEC
 	bool "NV Tegra Embedded Controller SMBus Interface"
 	depends on I2C && GPIOLIB && ARCH_TEGRA
+	select MFD_CORE
 	help
 	    Say Y here to enable support for a nVidia compliant embedded
 	    controller.