This was a big mess, rework the logic a bit so that we constrain
to a particular subtype and figure out the board support based
on that. This makes building subtype specific kernels supporting
multiple boards possible again.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

This adds preliminary support for the SH7785-based Highlander board.
Some of the Highlander support code is reordered so that most of it
can be reused directly.

This also plugs in missing SH7785 checks in the places that need it,
as this is the first board to support the CPU.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

This adds support for the Renesas SH7780 development boards,
R7780RP and R7780MP.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>