dma40: Improve the logic of stopping logical chan

dma40: Improve the logic of stopping logical chan

can be directly stopped by issuing a SUSPEND_REQ on the EE
bits. There is no need to suspend the physical channel and
restart it.

Also, the support for pre-V2 hw is discontinued.

EE bits for writing:

00: disable only if AS=11 or AS=00
01: enable
10: suspend_req only if AS=01 & EE=01 or EE=11
11: round / no change for writing

Signed-off-by: Narayanan G <narayanan.gopalakrishnan@stericsson.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>