Introduce a new function that indicates whether a given memory
region is required for a given version of IPA hardware.  Use it to
verify that all required regions are present during initialization.

Reorder the definitions of the memory region IDs to be based on
the version in which they're first defined.  Use "+" rather than
"and above" where defining the IPA versions in which memory IDs are
used, and indicate which regions are optional (many are not).
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>