dmaengine: ste_dma40: Declare memcpy config as static

Fix sparse warnings:

drivers/dma/ste_dma40.c:81:26: warning: symbol 'dma40_memcpy_conf_phy' was not declared. Should it be static?
drivers/dma/ste_dma40.c:95:26: warning: symbol 'dma40_memcpy_conf_log' was not declared. Should it be static?

Signed-off-by: Fabio Baltieri <fabio.baltieri@linaro.org>
Acked-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>