Add device nodes for the Serial Communication Interfaces with FIFO
(SCIF) on the Renesas R-Car V4H (R8A779G0) SoC, including DMA support.

Based on patches in the BSP by Takeshi Kihara and Vinh Nguyen.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/3f0ad7ce0fedfca2783001a6eb3eca96aea72115.1666361314.git.geert+renesas@glider.be