ARM: dts: imx6qdl-gw52xx: fix duplicate regulator naming

2 regulator descriptions carry identical naming.

This leads to following boot warning:
[    0.173138] debugfs: Directory 'vdd1p8' with parent 'regulator' already present!

Fix this by renaming the one used for audio.

Fixes: 5051bff3

 ("ARM: dts: imx: ventana: add LTC3676 PMIC support")
Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Koen Vandeputte <koen.vandeputte@ncentric.com>
Cc: stable@vger.kernel.org # v4.11
Signed-off-by: Shawn Guo <shawnguo@kernel.org>