net: ipa: use ipa_table_mem() in ipa_table_reset_add()

Similar to the previous commit, pass flags rather than a memory
region ID to ipa_table_reset_add(), and there use ipa_table_mem() to
look up the memory region affected based on those flags.

Currently all eight of these table memory regions are assumed to
exist, because they all have canaries within them.  Stop assuming
that will always be the case, and in ipa_table_reset_add() allow
these memory regions to be non-existent.

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