ARM: dts: am335x-wega: Add audio support

The wega board has a TLV320AIC3007 connected via McASP0. In the default
configuration, no external crystal is mounted. We run a system clock of
25 MHz, so we use the audio codec PLL for audio clock generation.

Signed-off-by: Stefan Müller-Klieser <s.mueller-klieser@phytec.de>
Reviewed-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>