i2c: stu300: Use proper printk format for iomem pointer

iomem pointers should be printed with pointer format to hide the
actual value and fix warnings when compiling on 64-bit platform (e.g. with
COMPILE_TEST):

    drivers/i2c/busses/i2c-stu300.c: In function ‘stu300_wait_while_busy’:
    drivers/i2c/busses/i2c-stu300.c:446:76: warning:
        cast from pointer to integer of different size [-Wpointer-to-int-cast]
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

drivers/i2c/busses/i2c-stu300.c

@@ -444,7 +444,7 @@ static int stu300_wait_while_busy(struct stu300_dev *dev)
 		       "Attempt: %d\n", i+1);
 
 		dev_err(&dev->pdev->dev, "base address = "
-			"0x%08x, reinit hardware\n", (u32) dev->virtbase);
+			"0x%p, reinit hardware\n", dev->virtbase);
 
 		(void) stu300_init_hw(dev);
 	}