mfd: si476x: Add header files and Kbuild plumbing

This patch adds all necessary header files and Kbuild plumbing for the
core driver for Silicon Laboratories Si476x series of AM/FM tuner
chips.

The driver as a whole is implemented as an MFD device and this patch
adds a core portion of it that provides all the necessary
functionality to the two other drivers that represent radio and audio
codec subsystems of the chip.

Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index 0676566..718e94a 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -134,6 +134,10 @@
 obj-$(CONFIG_MFD_TPS6586X)	+= tps6586x.o
 obj-$(CONFIG_MFD_VX855)		+= vx855.o
 obj-$(CONFIG_MFD_WL1273_CORE)	+= wl1273-core.o
+
+si476x-core-y := si476x-cmd.o si476x-prop.o si476x-i2c.o
+obj-$(CONFIG_MFD_SI476X_CORE)	+= si476x-core.o
+
 obj-$(CONFIG_MFD_CS5535)	+= cs5535-mfd.o
 obj-$(CONFIG_MFD_OMAP_USB_HOST)	+= omap-usb-host.o omap-usb-tll.o
 obj-$(CONFIG_MFD_PM8921_CORE) 	+= pm8921-core.o