ARM: dts: am335x-evm: Enable the McASP FIFO for audio

The use of FIFO in McASP can reduce the risk of audio under/overrun and
lowers the load on the memories since the DMA will operate in bursts.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>