dmaengine: qcom_hidma: correct channel QOS register offset

A regression was found while testing QOS with different channels.
The QOS register offset is 0x700 rather than 0x300.

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