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.c b/drivers/mfd/stmpe.c
index 3b6bfa7..02a17c3 100644
--- a/drivers/mfd/stmpe.c
+++ b/drivers/mfd/stmpe.c
@@ -1147,7 +1147,7 @@
 }
 
 /* Called from client specific probe routines */
-int stmpe_probe(struct stmpe_client_info *ci, int partnum)
+int stmpe_probe(struct stmpe_client_info *ci, enum stmpe_partnum partnum)
 {
 	struct stmpe_platform_data *pdata = dev_get_platdata(ci->dev);
 	struct device_node *np = ci->dev->of_node;