dmaengine: remove coh901318 driver

The ST-Ericsson U300 platform is getting removed, so this driver is no
longer needed.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Cc: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20210120131859.2056308-4-arnd@kernel.org


Signed-off-by: Vinod Koul <vkoul@kernel.org>