bluetooth: Fix potential assertion failure due to unaligned packet size

bluetooth: Fix potential assertion failure due to unaligned packet size

While reading from the SCO socket, there is no guarantee regarding the
resulting packet size. In some rare cases, it might not even match the
alignment expected in pa_source_post(), resulting in an assertion
failure inside pa_volume_memchunk():

I: [alsa-sink] module-loopback.c: Could not peek into queue
I: [alsa-sink] module-loopback.c: Could not peek into queue
I: [alsa-sink] module-loopback.c: Could not peek into queue
E: [bluetooth] sample-util.c: Assertion 'pa_frame_aligned(c->length, spec)' failed at pulsecore/sample-util.c:725, function pa_volume_memchunk(). Aborting.

Program received signal SIGABRT, Aborted.
[Switching to Thread 0x7fffda98f700 (LWP 8058)]
0x00007ffff6177935 in raise () from /lib64/libc.so.6
Missing separate debuginfos, use: debuginfo-install alsa-lib-1.0.26-1.fc17.x86_64 dbus-libs-1.4.10-7.fc17.x86_64 flac-1.2.1-9.fc17.x86_64 glibc-2.15-58.fc17.x86_64 gsm-1.0.13-6.fc17.x86_64 json-c-0.10-2.fc17.x86_64 libICE-1.0.8-1.fc17.x86_64 libSM-1.2.1-1.fc17.x86_64 libX11-1.5.0-2.fc17.x86_64 libXau-1.0.6-3.fc17.x86_64 libXext-1.3.1-1.fc17.x86_64 libXi-1.6.1-1.fc17.x86_64 libXtst-1.2.0-3.fc17.x86_64 libogg-1.3.0-1.fc17.x86_64 libsndfile-1.0.25-2.fc17.x86_64 libtool-ltdl-2.4.2-3.1.fc17.x86_64 libudev-182-3.fc17.x86_64 libuuid-2.21.2-3.fc17.x86_64 libvorbis-1.3.3-1.fc17.x86_64 libxcb-1.9-1.fc17.x86_64 speex-1.2-0.14.rc1.fc17.x86_64