SPI: cs_change not working properly

In file drivers/spi/spi-omap2-mcspi.c funcion omap2_mcspi_work()

```
/* ignore the "leave it on after last xfer" hint */
if (t->cs_change) {
omap2_mcspi_force_cs(spi, 0);
cs_active = 0;
}
```

Setting cs_change is supposed to keep the chip select pin active after returning from the function.
This code does not allow to keep the transaction alive.