i2c: Add entry for Designware I2C driver in Kconfig

This patch adds an entry for the Designware I2C driver in Kconfig.
Signed-off-by: NStefan Roese <sr@denx.de>
Cc: Heiko Schocher <hs@denx.de>
Reviewed-by: NBin Meng <bmeng.cn@gmail.com>

drivers/i2c/Kconfig

@@ -72,6 +72,14 @@ config SYS_I2C_CADENCE
 	  Say yes here to select Cadence I2C Host Controller. This controller is
 	  e.g. used by Xilinx Zynq.
 
+config SYS_I2C_DW
+	bool "Designware I2C Controller"
+	default n
+	help
+	  Say yes here to select the Designware I2C Host Controller. This
+	  controller is used in various SoCs, e.g. the ST SPEAr, Altera
+	  SoCFPGA, Synopsys ARC700 and some Intel x86 SoCs.
+
 config SYS_I2C_INTEL
 	bool "Intel I2C/SMBUS driver"
 	depends on DM_I2C