ARM: clean up per-processor check_bugs method call

Call the per-processor type check_bugs() method in the same way as we
do other per-processor functions - move the "processor." detail into
proc-fns.h.

Reviewed-by: Julien Thierry <julien.thierry@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>