ARM: dts: ux500: Add eSRAM nodes

The U8500 has 640 KB of eSRAM, split into 5 banks of 128 KB
each. Add this to the device tree, with ESRAM 0, 1+2 and 3+4
as separate devices, since these have different power domains.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20230417-ux500-dma40-cleanup-v2-8-cdaa68a4b863@linaro.org