ARM: move outer_cache declaration out of ifdef

commit 0b53c11d upstream.

Move the outer_cache declaration of the CONFIG_OUTER_CACHE ifdef so that
outer_cache can be used inside IS_ENABLED condition.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>