stagefright-plugins: Handle 32-bit floating point sample formats

 * Convert these to 24-bit PCM if the system is capable of it.
 * This also fixes that pesky ADSP crash.

Change-Id: Ia464d62f2b6f17986428f3e45ed61784d4c9006f
Merge pull request #2 from CyanogenMod/cm-11.0

stagefright-plugins: Handle 32-bit floating point sample formats