mfd: Remove MFD_CROS_EC_SPI depends on OF

The ChromeOS EC SPI transport driver has a dependency on OF because it
uses some OF helpers from the <linux/of.h> header. But there isn't a
need for an explicit dependency since the header has stub functions if
CONFIG_OF is not defined.

Also, MFD_CROS_EC_SPI already depends on MFD_CROS_EC which in turn has
a dependency on OF so in practice can't be selected without CONFIG_OF.
Signed-off-by: NJavier Martinez Canillas <javier.martinez@collabora.co.uk>
Signed-off-by: NLee Jones <lee.jones@linaro.org>

drivers/mfd/Kconfig

@@ -115,7 +115,7 @@ config MFD_CROS_EC_I2C
 
 config MFD_CROS_EC_SPI
 	tristate "ChromeOS Embedded Controller (SPI)"
-	depends on MFD_CROS_EC && CROS_EC_PROTO && SPI && OF
+	depends on MFD_CROS_EC && CROS_EC_PROTO && SPI
 
 	---help---
 	  If you say Y here, you get support for talking to the ChromeOS EC