Don't populate the read-only array ds_lut on the stack but instead it
static. Also makes the object code smaller by 163 bytes:

Before:
   text    data     bss     dec     hex filename
  23508    4796       0   28304    6e90 ./drivers/dma/sh/rz-dmac.o

After:
   text    data     bss     dec     hex filename
  23281    4860       0   28141    6ded ./drivers/dma/sh/rz-dmac.o

(gcc version 11.2.0)
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/20210915112038.12407-1-colin.king@canonical.comSigned-off-by: Vinod Koul <vkoul@kernel.org>