mfd: syscon: Support native-endian regmaps

The regmap devicetree binding documentation states that a native-endian
property should be supported as well as big-endian & little-endian,
however syscon in its duplication of the parsing of these properties
omits support for native-endian. Fix this by setting
REGMAP_ENDIAN_NATIVE when a native-endian property is found.

Cc: linux-mips@linux-mips.org
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Tested-by: Maciej W. Rozycki <macro@imgtec.com>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/syscon.c

@@ -75,6 +75,8 @@ static struct syscon *of_syscon_register(struct device_node *np)
 		syscon_config.val_format_endian = REGMAP_ENDIAN_BIG;
 	else if (of_property_read_bool(np, "little-endian"))
 		syscon_config.val_format_endian = REGMAP_ENDIAN_LITTLE;
+	else if (of_property_read_bool(np, "native-endian"))
+		syscon_config.val_format_endian = REGMAP_ENDIAN_NATIVE;
 
 	/*
 	 * search for reg-io-width property in DT. If it is not provided,