sh: Add SH7785 Highlander board support (R7785RP).

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: Paul Mundt <lethal@linux-sh.org>

arch/sh/tools/mach-types

@@ -26,6 +26,7 @@ SH03			SH_SH03
 LANDISK			SH_LANDISK
 R7780RP			SH_R7780RP
 R7780MP			SH_R7780MP
+R7785RP			SH_R7785RP
 TITAN			SH_TITAN
 SHMIN			SH_SHMIN
 7710VOIPGW		SH_7710VOIPGW