target-ppc: POWER8 supports the MSR_LE bit

Add MSR_LE to the msr_mask for POWER8.

Signed-off-by: Anton Blanchard <anton@samba.org>
target-ppc: POWER8 supports isel

POWER8 supports isel, so enable it in QEMU.

Signed-off-by: Anton Blanchard <anton@samba.org>
target-ppc: POWER7+ supports the MSR_VSX bit

Without MSR_VSX we die early during a Linux boot.

Signed-off-by: Anton Blanchard <anton@samba.org>
target-ppc: MSR_POW not supported on POWER7/7+/8

Remove MSR_POW from the msr_mask for POWER7/7+/8.

Signed-off-by: Anton Blanchard <anton@samba.org>