ARM: dts: am335x-wega: Change node name of sound card, remove underscores.

Change node name of sound card to recommended generic and remove also
further underscores in other node names.

Signed-off-by: Steffen Hemer <s.hemer@phytec.de>
Message-Id: <20230214132302.39087-3-s.hemer@phytec.de>
Signed-off-by: Tony Lindgren <tony@atomide.com>