powerpc: Use extended mnemonic for load immediate

4 jobs for vsx in 1 minute and 20 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Build
passed #583040
debian sid

00:01:20

passed #583043
docker windows 1607
msys2

00:01:03

passed #583041
docker windows 1607
vs2017 amd64

00:01:06

passed #583042
docker windows 1607
vs2017 x86

00:01:06