Define the Eagle/V3MSK board dependent parts of the RPC-IF device node.
Add device nodes for Spansion S25FS512S SPI flash and MTD partitions on it.

Based on the original patches by Dmitry Shifrin.
Signed-off-by: Dmitry Shifrin <dmitry.shifrin@cogentembedded.com>
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Link: https://lore.kernel.org/r/fca1d012-29bf-eead-1c0d-4dd837c0bc68@cogentembedded.comSigned-off-by: Geert Uytterhoeven <geert+renesas@glider.be>