This patch replaces the arch_identify() in system.h with a set of
cpu_is_XXX() macro's.  This allows for compile-time checking of the
target AT91 processor.

Original patch from David Brownell.
Signed-off-by: NAndrew Victor <andrew@sanpeople.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>