am7xxx: don't mention AM7XXX_DIRECTION_OUT in read_header()

The validity check in read_header() looks for:

	h->direction == AM7XXX_DIRECTION_IN

When this is false (direction is _not_equal_ to AM7XXX_DIRECTION_IN) it
cannot be said for sure that the direction field value is going to
really be AM7XXX_DIRECTION_OUT, technically the device may have put
anything there.

So, just report what happens don't try to overguess.