powerpc: Remove impossible mmu_psize_defs[] on nohash

Today there is:

  if e500 or 8xx
    if e500
      mmu_psize_defs[] =
    else if 8xx
      mmu_psize_defs[] =
    else
      mmu_psize_defs[] =
    endif
  endif

The else leg is dead definition.

Drop that else leg and rewrite as:

  if e500
    mmu_psize_defs[] =
  endif
  if 8xx
    mmu_psize_defs[] =
  endif

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/030a843449f348c0b709ca5349640624f36a016f.1663606876.git.christophe.leroy@csgroup.eu