i2c: i2c-cdns: Prevent early termination of write

During sequential loading of data, hold the bus to prevent controller
from sending stop signal in case no data is available in fifo.

Signed-off-by: Sai Pavan Boddu <sai.pavan.boddu@xilinx.com>
Reviewed-by: Ashok Reddy Soma <ashok.reddy.soma@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Link: https://lore.kernel.org/r/2407b39d305999cb42438c5423aebc3b514acabb.1646122610.git.michal.simek@xilinx.com