dmaengine: qcom_hidma: allow ACPI/DT parameters to be overridden

Parameters like maximum read/write request size and the maximum
number of active transactions are currently configured in DT/ACPI.

This patch allows a user to override these to fine tune performance
for their application.

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>