[OpenMP][NFC] Fix stale DeviceRTL header path in OpenMPIRBuilder (#185563)
The `\see` comment in `OpenMPIRBuilder.h` references
`openmp/libomptarget/deviceRTLs/common/include/target.h`. This file no
longer exists.
This patch updates the comment to point to the current correct header:
`openmp/device/include/Interface.h`.