k3dma: Fix "nobody cared" message seen on any error

k3dma: Fix "nobody cared" message seen on any error

As it was before, as soon as the DMAC IP felt there was an error
he would return IRQ_NONE since no actual transfer had completed.

After spinning on that for 100K interrupts, Linux yanks the IRQ with
a "nobody cared" error.

This patch lets it handle the interrupt and keep the IRQ alive.

Cc: Zhangfei Gao <zhangfei.gao@linaro.org>
Cc: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Cc: Vinod Koul <vinod.koul@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Andy Green <andy@warmcat.com>
Acked-by: Zhangfei Gao <zhangfei.gao@linaro.org>
Signed-off-by: Andy Green <andy.green@linaro.org>
[jstultz: Forward ported to mainline]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>