mfd: 88pm805: Fix potential NULL pdata dereference

User pass platform data to device, and platform data may be
NULL. Add the check for pdata.

Signed-off-by: Chao Xie <chao.xie@marvell.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

drivers/mfd/88pm805.c

@@ -243,7 +243,7 @@ static int pm805_probe(struct i2c_client *client,
 		goto err_805_init;
 	}
 
-	if (pdata->plat_config)
+	if (pdata && pdata->plat_config)
 		pdata->plat_config(chip, pdata);
 
 err_805_init: