dmaengine: ste_dma40: support more than 128 event lines

U8540 DMA controller is different from u9540 we need define new
registers and use them to support handling more than 128 event lines.

Signed-off-by: Tong Liu <tong.liu@stericsson.com>
Reviewed-by: Per Forlin <per.forlin@stericsson.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Fabio Baltieri <fabio.baltieri@linaro.org>