dmaengine: sirf-dma: remove unused ‘sdesc’

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

drivers/dma/sirf-dma.c: In function 'sirfsoc_dma_pm_suspend':
drivers/dma/sirf-dma.c:1014:27: warning: variable 'sdesc' set but not used [-Wunused-but-set-variable]

So remove it.

Signed-off-by: Vinod Koul <vinod.koul@intel.com>