sound trigger: more checks on IMemory received from client

Add a verification on actual size of the fd backing up the IMemory
recevied for sound model or recognition config.

Fix similar problem for AudioTrack shared buffer.

Bug: 78596657
Test: run POC. OK Google regression.
Change-Id: I7cb02785f8ba46c437c7fcaa5b821f4b7e3240a0