Replace
  "-" TYPE_POWERPC_CPU
when composing cpu type name from cpu model string literal
and the same pattern in format strings with
 POWERPC_CPU_TYPE_SUFFIX and POWERPC_CPU_TYPE_NAME(model)
macroses like we do in x86.

Later POWERPC_CPU_TYPE_NAME() will be used to define default
cpu type per machine type and as bonus it will be consistent
and easy grep-able pattern across all other targets that I'm
plannig to treat the same way.
Signed-off-by: NIgor Mammedov <imammedo@redhat.com>
Reviewed-by: NDavid Gibson <david@gibson.dropbear.id.au>
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>