rpc/bt: fix bt socket read

  * Fix BT socket read() to read until the specified number of bytes are
    read or fails.

  * Change GattReader to use AUTO for all device type since it doesn't
    seem to help.

MultiPart: 2/2

Change-Id: Ifea86fe11e82cdeb7e8e7b799025b35939aeedf3
1 file changed