gpio: rename pca9539 driver

First part of an extension to let the pca9539 driver support more chips,
starting with pca9534, pca9535, pca9536, pca9537, and pca9538.

This renames the files and modifies the Makefile.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/i2c/pca953x.h

@@ -0,0 +1,18 @@
+/* platform data for the PCA9539 16-bit I/O expander driver */
+
+struct pca9539_platform_data {
+	/* number of the first GPIO */
+	unsigned	gpio_base;
+
+	/* initial polarity inversion setting */
+	uint16_t	invert;
+
+	void		*context;	/* param to setup/teardown */
+
+	int		(*setup)(struct i2c_client *client,
+				unsigned gpio, unsigned ngpio,
+				void *context);
+	int		(*teardown)(struct i2c_client *client,
+				unsigned gpio, unsigned ngpio,
+				void *context);
+};