ARM: dts: imx7d-sdb: Fix regulator-usb-otg2-vbus node name

The two usb-otg regulators for imx7d-sdb are both called
"regulator-usb-otg1-vbus" and they effectively override each other.

This is most likely a copy-paste error.

Fixes: b877039a ("ARM: dts: imx7d-sdb: Adjust the regulator nodes")
Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>