i2c: i801: Add i801_simple_transaction(), complementing i801_block_transaction()

Factor out non-block pre/post processing to a new function
i801_simple_transaction(), complementing existing function
i801_block_transaction(). This makes i801_access() better readable.

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