Revert 130765 - alsa_output: Bounds check snd_pcm_avail_update.
Revert 130765 - alsa_output: Bounds check snd_pcm_avail_update.

Buggy ALSA drivers can at times return very large values from snd_pcm_avail_update.  There should never be more available frames than total frames in the buffer.

Patch by dgreid@chromium.org:
http://codereview.chromium.org/9963043/

BUG=chromium-os:26151
TEST=Manual, run a flash player looping alongside an aplay stress test and check that the flash video continues to output audio.

TBR=scherkus@chromium.org
Review URL: https://chromiumcodereview.appspot.com/9996001

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@130773 0039d316-1c4b-4281-b951-d872f2087c98

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