I2C: JZ4780: Fix bug for Ingenic X1000.

Only send "X1000_I2C_DC_STOP" when last byte, or it will cause
error when I2C write operation which should look like this:

device_addr + w, reg_addr, data;

But without this patch, it looks like this:

device_addr + w, reg_addr, device_addr + w, data;

Fixes: 21575a7a

 ("I2C: JZ4780: Add support for the X1000.")
Reported-by: 杨文龙 (Yang Wenlong) <ywltyut@sina.cn>
Tested-by: 杨文龙 (Yang Wenlong) <ywltyut@sina.cn>
Signed-off-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>