nvptx: Support '-march=sm_89'

nvptx: Support '-march=sm_89'

	gcc/
	* config/nvptx/nvptx-sm.def: Add '89'.
	* config/nvptx/nvptx-gen.h: Regenerate.
	* config/nvptx/nvptx-gen.opt: Likewise.
	* config/nvptx/nvptx.cc (first_ptx_version_supporting_sm): Adjust.
	* config/nvptx/nvptx.opt (-march-map=sm_89, -march-map=sm_90)
	(march-map=sm_90a): Likewise.
	* config.gcc: Likewise.
	* doc/invoke.texi (Nvidia PTX Options): Document '-march=sm_89'.
	* config/nvptx/gen-multilib-matches-tests: Extend.
	gcc/testsuite/
	* gcc.target/nvptx/march-map=sm_89.c: Adjust.
	* gcc.target/nvptx/march-map=sm_90.c: Likewise.
	* gcc.target/nvptx/march-map=sm_90a.c: Likewise.
	* gcc.target/nvptx/march=sm_89.c: New.
	libgomp/
	* testsuite/libgomp.c/declare-variant-3-sm89.c: New.
	* testsuite/libgomp.c/declare-variant-3.h: Adjust.