Some SoCs have multiple VIC devices.  Adapt the generic vic code
to allow multiple implementations to be handled.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Other machines may wish to make use of the VIC support code, so
move it to arch/arm/common.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>