dmaengine: ste_dma40: Get LCPA SRAM from SRAM node

Instead of passing the reserved SRAM as a "reg" field
look for a phandle to the LCPA SRAM memory so we can
use the proper SRAM device tree bindings for the SRAM.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20230417-ux500-dma40-cleanup-v3-2-60bfa6785968@linaro.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>