dmaengine: qcom_hidma: convert to DEFINE_SHOW_ATTRIBUTE

Use DEFINE_SHOW_ATTRIBUTE macro to simplify the code.

Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
Acked-by: Sinan Kaya <okaya@kernel.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>