dmaengine: pl330: Remove unused 'regs' variable in pl330_submit_req()

The 'void __iomem *regs' is not used in pl330_submit_req() function.
Remove it.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>