regmap: mmio: Fix value endianness selection

Currently when selecting value endianness we check the register
endiannes, not the value endianness.
Reported-by: Alexander Stein <alexander.stein@systec-electronic.com>
Tested-by: Alexander Stein <alexander.stein@systec-electronic.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/base/regmap/regmap-mmio.c

@@ -245,7 +245,7 @@ static struct regmap_mmio_context *regmap_mmio_gen_context(struct device *dev,
 	ctx->val_bytes = config->val_bits / 8;
 	ctx->clk = ERR_PTR(-ENODEV);
 
-	switch (config->reg_format_endian) {
+	switch (config->val_format_endian) {
 	case REGMAP_ENDIAN_DEFAULT:
 	case REGMAP_ENDIAN_LITTLE:
 #ifdef __LITTLE_ENDIAN