rtc: rv3028: Add missed check for devm_regmap_init_i2c()

rv3028_probe() misses a check for devm_regmap_init_i2c().
Add the missed check to fix it.

Fixes: e6e7376c ("rtc: rv3028: add new driver")
Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20200528103950.912353-1-hslester96@gmail.com

drivers/rtc/rtc-rv3028.c

@@ -755,6 +755,8 @@ static int rv3028_probe(struct i2c_client *client)
 		return -ENOMEM;
 
 	rv3028->regmap = devm_regmap_init_i2c(client, &regmap_config);
+	if (IS_ERR(rv3028->regmap))
+		return PTR_ERR(rv3028->regmap);
 
 	i2c_set_clientdata(client, rv3028);