Fix long standing multi playback/recording issues, caused by excessive interrupt clock timer reset, screwing interrupt generation for already active channels. Track moving DMA pointer and call buffer interrupt on each blocksize boundary.
Fix long standing multi playback/recording issues, caused by
excessive interrupt clock timer reset, screwing interrupt generation
for already active channels. Track moving DMA pointer and call buffer
interrupt on each blocksize boundary.

PR:		kern/109791
MFC after:	3 days

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