drivers: i2c: stm32 I2C V2 handles i2c_target processed_cb return code

Check the return code of the i2c_target_read/write callback function
is 0 before continuing the transmit/receive operation on I2C target
When Transmitting: 0 if data has been provided, then continue
When address matches: 0 if the write is accepted or
if more data can be requested depending on the transfer direction.

Signed-off-by: Francois Ramu <francois.ramu@st.com>