please test pcm patch

Hello All,
	Please test a pcm patch that releases the channel lock around
calls to uio move.  This is a more complete patch than the previous
one as it also does the _read routine.  I will ask the RE to commit
this if I hear a couple of "it works".

Pointed out by:	Artur Poplawski
Explained by:	Don Lewis

	--Mat

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