i2c: core: Fix spacing error by checkpatch

Fix the following checkpatch error:
 #614: FILE: drivers/i2c/i2c-core-base.c:614:
 +	len = acpi_device_modalias(dev, buf, PAGE_SIZE -1);
 	                                               ^
No functional changes.

Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>