regulator: anatop: set default voltage selector for pcie

Set the initial voltage selector for vddpcie in case it's disabled
by default.

This fixes the below warning:
20c8000.anatop:regulator-vddpcie: Failed to read a valid default voltage selector.
anatop_regulator: probe of 20c8000.anatop:regulator-vddpcie failed with error -22

Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: Robin Gong <yibin.gong@nxp.com>
Cc: Richard Zhu <hongxing.zhu@nxp.com>
Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: Mark Brown <broonie@kernel.org>