dm: gpio: pca953x: introduce driver model support for pca953x

Introduce a new driver that supports driver model for pca953x.
The pca953x chips are used as I2C I/O expanders.
This driver is designed to support the following chips:
"
4 bits: pca9536, pca9537
8 bits: max7310, max7315, pca6107, pca9534, pca9538, pca9554,
        pca9556, pca9557, pca9574, tca6408, xra1202
16 bits: max7312, max7313, pca9535, pca9539, pca9555, pca9575,
         tca6416
24 bits: tca6424
40 bits: pca9505, pca9698
"
But for now this driver only supports max 24 bits and pca953x compatible
chips. pca957x compatible chips are not supported now.
These can be addressed when we need to add such support for the different
chips.
This driver has been tested on i.MX6 SoloX Sabreauto board with max7310
i2c expander using gpio command as following:

=>gpio status -a
Bank gpio@30_:
gpio@30_0: input: 1 [ ]

=> dm tree:
 i2c         [   ]    |   |   `-- i2c@021a8000
 gpio        [   ]    |   |       |-- gpio@30
 gpio        [   ]    |   |       `-- gpio@32

Signed-off-by: Peng Fan <van.freenix@gmail.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Wenyou Yang <wenyou.yang@atmel.com>
Cc: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Cc: Purna Chandra Mandal <purna.mandal@microchip.com>
Cc: Thomas Chou <thomas@wytron.com.tw>
Cc: Bhuvanchandra DV <bhuvanchandra.dv@toradex.com>
Cc: Andrea Scian <andrea.scian@dave.eu>
Cc: Michal Simek <michal.simek@xilinx.com>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Fabio Estevam <fabio.estevam@nxp.com>
Acked-by: Simon Glass <sjg@chromium.org>
Tested-by: Michal Simek <michal.simek@xilinx.com> #on ZynqMP zcu102
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 2b4624d..e6337c2 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -143,4 +143,26 @@
 	help
 	  Supports GPIO access on Zynq SoC.
 
+config DM_PCA953X
+	bool "PCA95[357]x, PCA9698, TCA64xx, and MAX7310 I/O ports"
+	depends on DM_GPIO
+	help
+	  Say yes here to provide access to several register-oriented
+	  SMBus I/O expanders, made mostly by NXP or TI.  Compatible
+	  models include:
+
+	  4 bits:	pca9536, pca9537
+
+	  8 bits:	max7310, max7315, pca6107, pca9534, pca9538, pca9554,
+			pca9556, pca9557, pca9574, tca6408, xra1202
+
+	  16 bits:	max7312, max7313, pca9535, pca9539, pca9555, pca9575,
+			tca6416
+
+	  24 bits:	tca6424
+
+	  40 bits:	pca9505, pca9698
+
+	  Now, max 24 bits chips and PCA953X compatible chips are
+	  supported
 endmenu