mfd: max8997: Naturalise cross-architecture discrepancies

If we compile the MAX8997 for a 64bit architecture we receive the following
warnings:

  drivers/mfd/max8997.c: In function ‘max8997_i2c_get_driver_data’:
  drivers/mfd/max8997.c:173:10:
    warning: cast from pointer to integer of different size
     return (int)match->data;
            ^

Signed-off-by: Lee Jones <lee.jones@linaro.org>

include/linux/mfd/max8997-private.h

@@ -387,7 +387,7 @@ struct max8997_dev {
 	struct i2c_client *muic; /* slave addr 0x4a */
 	struct mutex iolock;
 
-	int type;
+	unsigned long type;
 	struct platform_device *battery; /* battery control (not fuel gauge) */
 
 	int irq;