msm: ipa3: SRAM NAT, DDR NAT, back-and-forth NAT

NAT can be run out SRAM, then DDR, then back-and-forth all relative to
the number of connections the NAT can hold.

Change-Id: Id20d7087e4e84fec826c72e29e50cae97f43191d
CRs-Fixed: 2578986
Signed-off-by: Perry Randise <prandise@codeaurora.org>