imx233: fix stmp3700 compilation

Change-Id: Ifafe2d2092032c3aa49d91e71c2e9b68c403cb92
imx233: don't use vbusvalid on stmp3700, doesn't work currently

Change-Id: Id5788ffed943cac0b394a32f9614b4ca1868875e
zenv: cleanup and set codec/plugin buffer sizes

Change-Id: I4738a4caa82350a46742b2735c28114bfbb256b6