gpio: generic: Add label to platform data

When registering more than one platform device, it is
useful to set the gpio chip label in the platform data.

Signed-off-by: Pawel Moll <pawel.moll@arm.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

include/linux/basic_mmio_gpio.h

@@ -19,6 +19,7 @@
 #include <linux/spinlock_types.h>
 
 struct bgpio_pdata {
+	const char *label;
 	int base;
 	int ngpio;
 };