regulator: fix null pointer check on regmap

The null pointer check on regmap that checks for a dev_get_regmap failure
is currently returning -ENOENT if the regmap succeeded. Fix this by adding
in the missing ! operator.

Fixes: 4fe66d5a ("regulator: Add support for QCOM PMIC VBUS booster")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Addresses-Coverity: ("Dereference after null check")
Link: https://lore.kernel.org/r/20200702115659.38208-1-colin.king@canonical.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/qcom_usb_vbus-regulator.c

@@ -49,7 +49,7 @@ static int qcom_usb_vbus_regulator_probe(struct platform_device *pdev)
 	}
 
 	regmap = dev_get_regmap(dev->parent, NULL);
-	if (regmap) {
+	if (!regmap) {
 		dev_err(dev, "Failed to get regmap\n");
 		return -ENOENT;
 	}