net: ipa: redefine struct ipa_mem_data

The ipa_mem_data structure type was never actually used.  Instead,
the IPA memory regions were defined using the ipa_mem structure.

Redefine struct ipa_mem_data so it encapsulates the array of IPA-local
memory region descriptors along with the count of entries in that
array.  Pass just an ipa_mem structure pointer to ipa_mem_init().

Rename the ipa_mem_data[] array ipa_mem_local_data[] to emphasize
that the memory regions it defines are IPA-local memory.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>