ARM: 7918/1: clean up cache handling in core code

We have a handy macro to replace open coded __cpuc_flush_dcache_area(()
and outer_clean_range() sequences. Let's use it. No functional change.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>