[OpenMP] Remove omptarget-nvptx from deps as it is no longer a valid target

`omptarget-nvptx` is still a dependence for `check-libomptarget-nvtpx`
although it has been removed by D94573.

Reviewed By: JonChesterfield

Differential Revision: https://reviews.llvm.org/D94725

GitOrigin-RevId: 547b032ccc8e1da5d1716afeb0afa8988e129fd0
1 file changed