btaa: fix static packed BtaaHciPacket struct

Update the BtaaHciPacket to not use packet pragma as it is platform
dependent. Further updated the HciProcessor to eliminate static
declarations.

Tag: #feature
Bug: 187019165
Test: mmma -j system/bt
BYPASS_LONG_LINES_REASON: consist with gd format

Change-Id: I82bf7fcfa50c9911a8b7cdc69e0da68eb2b80a35