Sending ESP a command caused it to trigger DMA immediately
even if DMA was not enabled at the DMA controller.

Add a signal from DMA controller to ESP to tell ESP about changes in
DMA enable bit. Also use the correct function for setting up GPIO outputs.

This fixes NetBSD 1.6.1 through 3.0 boot.

Thanks to Artyom Tarasenko for extensive debugging of the problem.

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>