target-ppc: remove embedded MMU SPRs from 970, P5+/7/7+/8 PowerISA 2.04+ puts MMUCFG and MMUCSR0 SPRs to "E" (embedded) category so remove it from POWER7/8 class as it is "S" (server) category. Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> Signed-off-by: Alexander Graf <agraf@suse.de>