dmaengine: shdma: r8a73a4: Make dma_ts_shift[] static

dma_ts_shift[] isn't used outside this source file. All other users use
the definition from arch/arm/mach-shmobile/dma-register.h.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>