dmaengine: pl330: remove unused ‘regs’

In pl330_add(), variable ‘regs’ is initialized but never used, which
leads to warning with W=1.

drivers/dma/pl330.c: In function 'pl330_add':
drivers/dma/pl330.c:1891:16: warning: variable 'regs' set but not used [-Wunused-but-set-variable]

So remove it.

Cc: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>