i2c: iproc: generate stop event for slave writes

When slave status is I2C_SLAVE_RX_END, generate I2C_SLAVE_STOP
event to i2c_client.

Fixes: c245d94e ("i2c: iproc: Add multi byte read-write support for slave mode")
Signed-off-by: Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>