i2c: sis630: clear sticky bits

The sticky bits must be cleared at the end of the transaction by writing
a 1 to all fields.

Datasheet:
	SMBus Status (SMB_STS)
	The following registers are all sticky bits and only can be
	cleared by writing a one to their corresponding fields.

Signed-off-by: Amaury Decrême <amaury.decreme@gmail.com>
Reviewed-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Wolfram Sang <wolfram@the-dreams.de>