dt-bindings: sound: wm8994: Correct required supplies based on actual implementaion

dt-bindings: sound: wm8994: Correct required supplies based on actual implementaion

[ Upstream commit 8c149b7d75e53be47648742f40fc90d9fc6fa63a ]

The required supplies in bindings were actually not matching
implementation making the bindings incorrect and misleading.  The Linux
kernel driver requires all supplies to be present.  Also for wlf,wm8994
uses just DBVDD-supply instead of DBVDDn-supply (n: <1,3>).

Reported-by: Jonathan Bakker <xc-racer2@live.ca>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20200501133534.6706-1-krzk@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>