For PR103623 I fixed unpack, but pack is broken as well, as reported in
PR105334. Fixing that is a bit more code, but it is pretty simple code
nonetheless.
PR target/105334
* config/rs6000/rs6000.md (pack<mode> for FMOVE128): New expander.
(pack<mode> for FMOVE128): Rename and split the insn_and_split to...
(pack<mode>_hard for FMOVE128): ... this...
(pack<mode>_soft for FMOVE128): ... and this.