Convert CONFIG_SYS_I2C_SOFT et al to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_I2C_SOFT
   CONFIG_SYS_I2C_SOFT_SPEED
   CONFIG_SYS_I2C_SOFT_SLAVE

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig
index a50c1f3..4da074d 100644
--- a/drivers/i2c/Kconfig
+++ b/drivers/i2c/Kconfig
@@ -437,6 +437,25 @@
 	  bus. Devices can be attached to the bus using the device tree
 	  which specifies the driver to use.  See sandbox.dts as an example.
 
+config SYS_I2C_SOFT
+	bool "Legacy software I2C interface"
+	help
+	  Enable the legacy software defined I2C interface
+
+config SYS_I2C_SOFT_SPEED
+	int "Software I2C bus speed"
+	depends on SYS_I2C_SOFT
+	default 100000
+	help
+	  Speed of the software I2C bus
+
+config SYS_I2C_SOFT_SLAVE
+	hex "Software I2C slave address"
+	depends on SYS_I2C_SOFT
+	default 0xfe
+	help
+	  Slave address of the software I2C bus
+
 config SYS_I2C_OCTEON
 	bool "Octeon II/III/TX/TX2 I2C driver"
 	depends on (ARCH_OCTEON || ARCH_OCTEONTX || ARCH_OCTEONTX2) && DM_I2C