[nvptx] Handle V2DI/V2SI mode in nvptx_gen_shuffle

[nvptx] Handle V2DI/V2SI mode in nvptx_gen_shuffle

With the pr96628-part1.f90 source and -ftree-slp-vectorize, we run into an
ICE due to the fact that V2DI mode is not handled in nvptx_gen_shuffle.

Fix this by adding handling of V2DI as well as V2SI mode in
nvptx_gen_shuffle.

Build and reg-tested on x86_64 with nvptx accelerator.

gcc/ChangeLog:

	PR target/96428
	* config/nvptx/nvptx.c (nvptx_gen_shuffle): Handle V2SI/V2DI.

libgomp/ChangeLog:

	PR target/96428
	* testsuite/libgomp.oacc-fortran/pr96628-part1.f90: New test.
	* testsuite/libgomp.oacc-fortran/pr96628-part2.f90: New test.