[media] si4713: fix Kconfig dependencies

The SI4713 select should be I2C_SI4713 and the USB driver needs to depend on
I2C as well.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Reported-by: Paul Bolle <pebolle@tiscali.nl>
Reported-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

drivers/media/radio/si4713/Kconfig

 config USB_SI4713
 	tristate "Silicon Labs Si4713 FM Radio Transmitter support with USB"
-	depends on USB && RADIO_SI4713
-	select SI4713
+	depends on USB && I2C && RADIO_SI4713
+	select I2C_SI4713
 	---help---
 	  This is a driver for USB devices with the Silicon Labs SI4713
 	  chip. Currently these devices are known to work.
@@ -16,7 +16,7 @@ config USB_SI4713
 config PLATFORM_SI4713
 	tristate "Silicon Labs Si4713 FM Radio Transmitter support with I2C"
 	depends on I2C && RADIO_SI4713
-	select SI4713
+	select I2C_SI4713
 	---help---
 	  This is a driver for I2C devices with the Silicon Labs SI4713
 	  chip.