regulator: mt6315: Fix function prototype for mt6315_map_mode

The .of_map_mode should has below function prototype:
	unsigned int (*of_map_mode)(unsigned int mode);

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Link: https://lore.kernel.org/r/20210530022109.425054-1-axel.lin@ingics.com
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/mt6315-regulator.c

@@ -59,7 +59,7 @@ static const struct linear_range mt_volt_range1[] = {
 	REGULATOR_LINEAR_RANGE(0, 0, 0xbf, 6250),
 };
 
-static unsigned int mt6315_map_mode(u32 mode)
+static unsigned int mt6315_map_mode(unsigned int mode)
 {
 	switch (mode) {
 	case MT6315_BUCK_MODE_AUTO: