This patch introduces the outer_cache_fns.sync function pointer together
with the OUTER_CACHE_SYNC config option that can be used to drain the
write buffer of the outer cache.
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

To avoid #include collisions with subsequent patches in the series, this
patch moves the outer_cache definitions to a separate asm/outercache.h
file.
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>