i2c: octeon: Missing AAK flag in case of I2C_M_RECV_LEN

During receive the controller requires the AAK flag for all
bytes but the final one. This was wrong in case of I2C_M_RECV_LEN,
where the decision if the final byte is to be transmitted
happened before adding the additional received length byte.

Set the AAK flag if additional bytes are to be received.

Signed-off-by: Jan Glauber <jglauber@cavium.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>