arm64: renesas: Deduplicate R-Car Gen4 board files

All R-Car Gen4 board files are copies of one another at this point.
Deduplicate them into single board/renesas/rcar-common/gen4-common.c
and remove all the duplicates. The one exception is R-Car V3U Falcon
board, which enables RWDT reset in board_init(), conditionally build
RWDT enablement in board_init() in the new common code for V3U.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
8 files changed