regulator: fan53880: Fix vsel_mask setting for FAN53880_BUCK

According to the datasheet:
REGISTER DETAILS − 0x02 BUCK, BUCK_OUT is BIT0 ~ BIT7.

So vsel_mask for FAN53880_BUCK should be 0xFF.

Fixes: e6dea51e ("regulator: fan53880: Add initial support")
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Link: https://lore.kernel.org/r/20210607142907.1599905-1-axel.lin@ingics.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/fan53880.c

@@ -77,7 +77,7 @@ static const struct regulator_desc fan53880_regulators[] = {
 		},
 		.n_linear_ranges = 2,
 		.vsel_reg =	   FAN53880_BUCKVOUT,
-		.vsel_mask =	   0x7f,
+		.vsel_mask =	   0xff,
 		.enable_reg =	   FAN53880_ENABLE,
 		.enable_mask =	   0x10,
 		.enable_time =	   480,