gpio: loongson: Add Loongson-3A/3B GPIO driver support

Improve Loongson-2's GPIO driver to support Loongson-3A/3B, and update
Loongson-3's default config file.

Acked-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Huacai Chen <chenhc@lemote.com>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 473511f..41d91b6 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -509,10 +509,10 @@
 	  VHDL IP core library.
 
 config GPIO_LOONGSON
-	bool "Loongson-2 GPIO support"
-	depends on CPU_LOONGSON2
+	bool "Loongson-2/3 GPIO support"
+	depends on CPU_LOONGSON2 || CPU_LOONGSON3
 	help
-	  driver for GPIO functionality on Loongson-2F processors.
+	  driver for GPIO functionality on Loongson-2F/3A/3B processors.
 
 config GPIO_TB10X
 	bool