testsuite, rs6000: Replace powerpc_vsx_ok with powerpc_altivec etc.

This is a follow up patch for the previous patch adjusting
powerpc_vsx_ok with powerpc_vsx, focusing on those test cases
which don't really require VSX feature but used powerpc_vsx_ok
before, they actually require some other effective target check,
like some of them just require ALTIVEC feature, some of them
just require hard float support, and some of them just require
ISA 2.06 etc..

By the way, ppc-fpconv-4.c is the only one missing powerpc_fprs
among ppc-fpconv-*.c after this replacement, so I also fix it
here.

	PR testsuite/114842

gcc/testsuite/ChangeLog:

	* gcc.target/powerpc/bswap64-2.c: Replace powerpc_vsx_ok check with
	has_arch_pwr7.
	* gcc.target/powerpc/ppc-fpconv-2.c: Replace powerpc_vsx_ok check with
	powerpc_fprs.
	* gcc.target/powerpc/ppc-fpconv-6.c: Likewise.
	* gcc.target/powerpc/ppc-pow.c: Likewise.
	* gcc.target/powerpc/ppc-target-1.c: Likewise.
	* gcc.target/powerpc/ppc-target-2.c: Likewise.
	* gcc.target/powerpc/ppc-target-3.c: Likewise.
	* gcc.target/powerpc/ppc-target-4.c: Likewise.
	* gcc.target/powerpc/ppc-fpconv-4.c: Check for powerpc_fprs.
	* gcc.target/powerpc/fold-vec-select-char.c: Replace powerpc_vsx_ok
	with powerpc_altivec check and move it after dg-options line.
	* gcc.target/powerpc/fold-vec-select-float.c: Likewise.
	* gcc.target/powerpc/fold-vec-select-int.c: Likewise.
	* gcc.target/powerpc/fold-vec-select-short.c: Likewise.
	* gcc.target/powerpc/p9-novsx.c: Likewise.
	* gcc.target/powerpc/p9-options-1.c: Likewise.