[RS6000] power10 scan-assembler tests

[RS6000] power10 scan-assembler tests

On power10 these are "dg-do run" tests, so need -save-temps for the
assembler scanning.

	* gcc.target/powerpc/vsx-load-element-extend-char.c: Add -save-temps.
	* gcc.target/powerpc/vsx-load-element-extend-int.c: Likewise.
	* gcc.target/powerpc/vsx-load-element-extend-longlong.c: Likewise.
	* gcc.target/powerpc/vsx-load-element-extend-short.c: Likewise.
	* gcc.target/powerpc/vsx-store-element-truncate-char.c: Likewise.
	* gcc.target/powerpc/vsx-store-element-truncate-int.c: Likewise.
	* gcc.target/powerpc/vsx-store-element-truncate-longlong.c: Likewise.
	* gcc.target/powerpc/vsx-store-element-truncate-short.c: Likewise.