This reduces vmlinux text size by 1kB and data by 1.5kB with a small
build!
Signed-off-by: NNicholas Piggin <npiggin@gmail.com>
[mpe: Add the recently added CPU_FTRS_POWER9_DD2_2 to the little
      endian possible mask as noticed by Nick.]
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>