i2c: add support for Diolan DLN-2 USB-I2C adapter

This patch adds support for the Diolan DLN-2 I2C master module. Due
to hardware limitations it does not support SMBUS quick commands.

Information about the USB protocol interface can be found in the
Programmer's Reference Manual [1], see section 6.2.2 for the I2C
master module commands and responses.

[1] https://www.diolan.com/downloads/dln-api-manual.pdf

Signed-off-by: Laurentiu Palcu <laurentiu.palcu@intel.com>
Signed-off-by: Octavian Purdila <octavian.purdila@intel.com>
Acked-by: Wolfram Sang <wsa@the-dreams.de>
Reviewed-by: Johan Hovold <johan@kernel.org>
[Lee: Fixed some whitespace issues in Kconfig]
Signed-off-by: Lee Jones <lee.jones@linaro.org>
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 917c358..b4d135c 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -881,6 +881,16 @@
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-diolan-u2c.
 
+config I2C_DLN2
+       tristate "Diolan DLN-2 USB I2C adapter"
+       depends on MFD_DLN2
+       help
+	 If you say yes to this option, support will be included for Diolan
+	 DLN2, a USB to I2C interface.
+
+	 This driver can also be built as a module.  If so, the module
+	 will be called i2c-dln2.
+
 config I2C_PARPORT
 	tristate "Parallel port adapter"
 	depends on PARPORT