i2c: designware-baytrail: another fixup for proper Kconfig dependencies

IOSF_MBI is tristate. Baytrail driver isn't.

Reported-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: David E. Box <david.e.box@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 3de426e..81a3ce9 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -477,7 +477,7 @@
 
 config I2C_DESIGNWARE_BAYTRAIL
 	bool "Intel Baytrail I2C semaphore support"
-	depends on I2C_DESIGNWARE_PLATFORM && IOSF_MBI && ACPI
+	depends on I2C_DESIGNWARE_PLATFORM && IOSF_MBI=y && ACPI
 	help
 	  This driver enables managed host access to the PMIC I2C bus on select
 	  Intel BayTrail platforms using the X-Powers AXP288 PMIC. It allows