doc: prettify OPAL_PCI_SET_MVE
doc: prettify OPAL_PCI_SET_MVE

Signed-off-by: Stewart Smith <ec31ab75ddf977353c8f660f92ea8b23f64aef25@linux.ibm.com>

shenki/skiboot,qemu/skiboot,open-power/skiboot,shenki/skiboot,qemu/skiboot,legoater/skiboot,stewart-ibm/skiboot,open-power/skiboot,stewart-ibm/skiboot,shenki/skiboot,qemu/skiboot,stewart-ibm/skiboot,open-power/skiboot,legoater/skiboot,qemu/skiboot,shenki/skiboot,legoater/skiboot,qemu/skiboot,open-power/skiboot,legoater/skiboot,legoater/skiboot,open-power/skiboot,shenki/skiboot