xilinx_xiic: Fix fill tx fifo loop

xilinx_xiic: Fix fill tx fifo loop

Comparison should be against the actual message length, not loop index.

len is used for stopping while loop, pos is position in message.
stop should be sent when entire message is sent, not when
len and pos meet.

hs: fixed DOS line endings

Signed-off-by: Tomas Melin <tomas.melin@vaisala.com>