gpio: gpio-generic: Add 16 and 32 bit big endian byte order support

There is no general support for 64-bit big endian accesses, so that is
left unsupported.

Signed-off-by: Andreas Larsson <andreas@gaisler.com>
Acked-by: Anton Vorontsov <anton@enomsg.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/include/linux/basic_mmio_gpio.h b/include/linux/basic_mmio_gpio.h
index 1c504ca..d8a97ec 100644
--- a/include/linux/basic_mmio_gpio.h
+++ b/include/linux/basic_mmio_gpio.h
@@ -72,5 +72,6 @@
 #define BGPIOF_BIG_ENDIAN		BIT(0)
 #define BGPIOF_UNREADABLE_REG_SET	BIT(1) /* reg_set is unreadable */
 #define BGPIOF_UNREADABLE_REG_DIR	BIT(2) /* reg_dir is unreadable */
+#define BGPIOF_BIG_ENDIAN_BYTE_ORDER	BIT(3)
 
 #endif /* __BASIC_MMIO_GPIO_H */