Regenerate some regformats/rs6000/*.dat files

If I remove all regformats/*.dat files and run
make GDB=/scratch/yao/gdb/build-git/all-targets/gdb/gdb all, some
powerpc .dat files are not generated.

This patch fixes it by adding them to WHICH, so these .dat files can
be generated.

gdb:

2016-10-05  Yao Qi  <yao.qi@linaro.org>

	* features/Makefile (WHICH): Add
	rs6000/powerpc-isa205-32l, rs6000/powerpc-isa205-64l,
	rs6000/powerpc-isa205-altivec32l, rs6000/powerpc-isa205-altivec64l,
	rs6000/powerpc-isa205-vsx32l and rs6000/powerpc-isa205-vsx64l.
	* regformats/rs6000/powerpc-isa205-32l.dat: Regenerated.
	* regformats/rs6000/powerpc-isa205-64l.dat: Likewise.
	* regformats/rs6000/powerpc-isa205-altivec32l.dat: Likewise.
	* regformats/rs6000/powerpc-isa205-altivec64l.dat: Likewise.
	* regformats/rs6000/powerpc-isa205-vsx32l.dat: Likewise.
	* regformats/rs6000/powerpc-isa205-vsx64l.dat: Likewise.