regulator: mpq7920: Fix Woverflow warning on conversion

Fix warning Woverflow on type conversion reported on x86.

Fixes: 6501c1f5 (regulator: mpq7920: add mpq7920 regulator driver)
Signed-off-by: Saravanan Sekar <sravanhome@gmail.com>
Link: https://lore.kernel.org/r/20200110102220.7163-1-sravanhome@gmail.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/mpq7920.c

@@ -221,7 +221,7 @@ static int mpq7920_parse_cb(struct device_node *np,
 	if (of_property_read_bool(np, "mps,buck-ovp-disable")) {
 		regmap_update_bits(config->regmap,
 				MPQ7920_BUCK1_REG_B + (rdesc->id * 4),
-				BIT(6), ~BIT(6));
+				MPQ7920_MASK_OVP, MPQ7920_OVP_DISABLE);
 	}
 
 	ret = of_property_read_u8(np, "mps,buck-phase-delay", &val);

drivers/regulator/mpq7920.h

@@ -55,6 +55,8 @@
 #define MPQ7920_MASK_SWITCH_FREQ	0x30
 #define MPQ7920_MASK_BUCK_PHASE_DEALY	0x30
 #define MPQ7920_MASK_DVS_SLEWRATE	0xc0
+#define MPQ7920_MASK_OVP		0x40
+#define MPQ7920_OVP_DISABLE		~(0x40)
 #define MPQ7920_DISCHARGE_ON		0x1
 
 #define MPQ7920_REGULATOR_EN_OFFSET	7