dm: gpio: add BCM6345 gpio driver

This driver is based on linux/arch/mips/bcm63xx/gpio.c, simplified to allow
defining one or two independent banks for each Broadcom SoC.

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 0ca845f..03df558 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -16,6 +16,7 @@
 
 obj-$(CONFIG_AT91_GPIO)	+= at91_gpio.o
 obj-$(CONFIG_ATMEL_PIO4)	+= atmel_pio4.o
+obj-$(CONFIG_BCM6345_GPIO)	+= bcm6345_gpio.o
 obj-$(CONFIG_INTEL_ICH6_GPIO)	+= intel_ich6_gpio.o
 obj-$(CONFIG_INTEL_BROADWELL_GPIO)	+= intel_broadwell_gpio.o
 obj-$(CONFIG_KIRKWOOD_GPIO)	+= kw_gpio.o