mfd: stmpe: Rid data size incompatibility warn when building for 64bit

Extinguishes:

../drivers/mfd/stmpe-i2c.c: In function ‘stmpe_i2c_probe’:
../drivers/mfd/stmpe-i2c.c:88:13:
	warning: cast from pointer to integer of different size
	partnum = (int)of_id->data;

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
diff --git a/drivers/mfd/stmpe-i2c.c b/drivers/mfd/stmpe-i2c.c
index a45f9c0..5c054031c 100644
--- a/drivers/mfd/stmpe-i2c.c
+++ b/drivers/mfd/stmpe-i2c.c
@@ -68,7 +68,7 @@
 static int
 stmpe_i2c_probe(struct i2c_client *i2c, const struct i2c_device_id *id)
 {
-	int partnum;
+	enum stmpe_partnum partnum;
 	const struct of_device_id *of_id;
 
 	i2c_ci.data = (void *)id;
@@ -85,7 +85,7 @@
 		dev_info(&i2c->dev, "matching on node name, compatible is preferred\n");
 		partnum = id->driver_data;
 	} else
-		partnum = (int)of_id->data;
+		partnum = (enum stmpe_partnum)of_id->data;
 
 	return stmpe_probe(&i2c_ci, partnum);
 }