i2c: i801: Call i801_check_pre() from i801_access()

This avoids code duplication, in a next step we'll call
i801_check_post() from i801_transaction() as well.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Wolfram Sang <wsa@kernel.org>