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.h b/drivers/mfd/stmpe.h
index 9e4d21d..2d045f2 100644
--- a/drivers/mfd/stmpe.h
+++ b/drivers/mfd/stmpe.h
@@ -97,7 +97,7 @@
 	void (*init)(struct stmpe *stmpe);
 };
 
-int stmpe_probe(struct stmpe_client_info *ci, int partnum);
+int stmpe_probe(struct stmpe_client_info *ci, enum stmpe_partnum partnum);
 int stmpe_remove(struct stmpe *stmpe);
 
 #define STMPE_ICR_LSB_HIGH	(1 << 2)