k3dma: Fix hisi burst clipping

k3dma: Fix hisi burst clipping

Max burst len is a 4-bit field, but at the moment it's clipped with
a 5-bit constant... reduce it to that which can be expressed

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>