rs6000: Support [u]mod<mode>3 for vector modulo insns

rs6000: Support [u]mod<mode>3 for vector modulo insns

This patch is to make Power10 newly introduced vector
modulo instructions exploited in vectorized loops, it
just simply renames existing define_insns as standard
pattern names.

gcc/ChangeLog:

	* config/rs6000/vsx.md (mods_<mode>): Rename to...
	(mod<mode>3): ... this.
	(modu_<mode>): Rename to...
	(umod<mode>3): ... this.
	* config/rs6000/rs6000-builtin.def (MODS_V2DI, MODS_V4SI, MODU_V2DI,
	MODU_V4SI): Adjust.

gcc/testsuite/ChangeLog:

	* gcc.target/powerpc/mod-vectorize.c: New test.