Bluetooth: ATT: Fix not responding when there is a request in parallel
Bluetooth: ATT: Fix not responding when there is a request in parallel

If there is a request ongoing it may block responses to be generated
since they were using the same buffer pool, so this introduces a
dedicated pool for responses making the code able to act as both
server and client at same time.

Change-Id: I5fe3e19f9c5c0c2e0dfadedf77b7684f0960572c
Signed-off-by: Luiz Augusto von Dentz <8530c5ea66a1bdbc08f98bfcf183c8be901b5990@intel.com>

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