gpio: gpio driver for max7301 SPI GPIO expander

Maxim's MAX7301 is an SPI GPIO expander with 28 GPIOs.  Note: MAX7301's
interrupt feature is not supported yet.

[akpm@linux-foundation.org: coding-style fixes]
[g.liakhovetski@pengutronix.de: Fix inaccuracies in comments, check spi_setup()
return code, mask off high byte in max7301_read()]
Signed-off-by: Juergen Beisert <j.beisert@pengutronix.de>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Russell King <rmk@arm.linux.org.uk>
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>
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index fdde992..16e796d 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -4,6 +4,7 @@
 
 obj-$(CONFIG_HAVE_GPIO_LIB)	+= gpiolib.o
 
+obj-$(CONFIG_GPIO_MAX7301)	+= max7301.o
 obj-$(CONFIG_GPIO_MCP23S08)	+= mcp23s08.o
 obj-$(CONFIG_GPIO_PCA953X)	+= pca953x.o
 obj-$(CONFIG_GPIO_PCF857X)	+= pcf857x.o