mfd: max8998: Naturalise cross-architecture discrepancies

If we compile the MAX8998 for a 64bit architecture we receive the following
warnings:

  drivers/mfd/max8998.c: In function ‘max8998_i2c_get_driver_data’:
  drivers/mfd/max8998.c:178:10:
    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/max8998-private.h

@@ -163,7 +163,7 @@ struct max8998_dev {
 	int ono;
 	u8 irq_masks_cur[MAX8998_NUM_IRQ_REGS];
 	u8 irq_masks_cache[MAX8998_NUM_IRQ_REGS];
-	int type;
+	unsigned long type;
 	bool wakeup;
 };