cache: Expand the APIs for cache flushing

The only two supported operations for data caches in the cache framework
are currently arch_dcache_flush() and arch_dcache_invd().

This is quite restrictive because for some architectures we also want to
control i-cache and in general we want a finer control over what can be
flushed, invalidated or cleaned. To address these needs this patch
expands the set of operations that can be performed on data and
instruction caches, adding hooks for the operations on the whole cache,
a specific level or a specific address range.

Signed-off-by: Carlo Caione <ccaione@baylibre.com>