dmaengine: coh901318: Fix a double-lock bug

The function coh901318_alloc_chan_resources() calls spin_lock_irqsave()
before calling coh901318_config().
But coh901318_config() calls spin_lock_irqsave() again in its
definition, which may cause a double-lock bug.

Because coh901318_config() is only called by
coh901318_alloc_chan_resources(), the bug fix is to remove the
calls to spin-lock and -unlock functions in coh901318_config().

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>