[ARM] 3590/1: AT91RM9200 Platform devices support

Patch from Andrew Victor

This patch includes the structures and exported functions required for
the platform-device support (added in patch 3585/1).

Also adds the arch_identify() function for run-time detection of which
AT91 processor the code is running on.  [Original patch from Ivan
Kokshaysky]

Signed-off-by: Andrew Victor <andrew@sanpeople.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>