ARM: rmobile: Convert to bootm_size

ARM: rmobile: Convert to bootm_size

Convert all Renesas R-Car boards to bootm_size of 256 MiB and drop both
fdt_high and initrd_high. This change implies that the FDT and initrd
will always be copied into the first 256 MiB of RAM instead of being
used in place, which can cause various kinds of inobvious problems.

The simpler problems include FDT or initrd being overwritten or being
used from unaligned addresses, especially on ARM64. The overhead of
copying the FDT to aligned location is negligible and these problems
go away, so the benefit is significant.

Regarding alignment problems with fitImage. The alignment of DT properties
is always 32 bits, which implies that the alignment of the "data" property
in fitImage is also 32 bits. The /incbin/ syntax plays no role here. The
kernel expects all elements, including DT and initrd, to be aligned to
64 bits on ARM64, thus using them in place may not be possible. Using the
bootm_size assures correct alignment, again with negligible overhead.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
Cc: Tom Rini <trini@konsulko.com>