dmaengine: ppc4xx: make ppc440spe_adma_chan_list static

The ppc440spe_adma_chan_list file-scope variable is not used outside of
the unit so it can be made static.
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20201019155756.21445-1-krzk@kernel.orgSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/ppc4xx/adma.c

@@ -69,7 +69,7 @@ struct ppc_dma_chan_ref {
 };
 
 /* The list of channels exported by ppc440spe ADMA */
-struct list_head
+static struct list_head
 ppc440spe_adma_chan_list = LIST_HEAD_INIT(ppc440spe_adma_chan_list);
 
 /* This flag is set when want to refetch the xor chain in the interrupt