[ARM] 5460/1: Orion: reduce namespace pollution

[ARM] 5460/1: Orion: reduce namespace pollution

Symbols like SOFT_RESET are way too generic to be exported at large.
To avoid this, let's move the mbus bridge register defines into a
separate file and include it where needed.  This affects mach-kirkwood,
mach-loki, mach-mv78xx0 and mach-orion5x simultaneously as they all
share code in plat-orion which relies on those defines.

Some other defines have been moved to narrower scopes, or simply deleted
when they had no user.

This fixes compilation problem with mpt2sas on the above listed
platforms.

Signed-off-by: Nicolas Pitre <nico@marvell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>