arm64: dts: imx93-kontron: Fix SD card IO voltage control
The OSM-S i.MX93 SoM doesn't have the VSELECT signal of the USDHC
controller connected to the PMICs SD_VSEL input. Instead SD_VSEL
is hardwired to low level. Let the driver know this in order to
use the proper register for reading and writing the voltage level.
This fixes SD card access with the latest hardware revision of
the Kontron OSM-S i.MX93 SoM.