armv8: disable for now PMUSERENR_EL0 because QEMU version <2.6.0 doesn't support it
armv8: disable for now PMUSERENR_EL0 because QEMU version <2.6.0 doesn't support it

Signed-off-by: Adam Turowski <1fa21b9d4d85b20a0227f7f4b2c1dcaee6317d80@inf.ethz.ch>

kishoredbn/barrelfish,kishoredbn/barrelfish,BarrelfishOS/barrelfish,BarrelfishOS/barrelfish,BarrelfishOS/barrelfish,BarrelfishOS/barrelfish,kishoredbn/barrelfish,BarrelfishOS/barrelfish,kishoredbn/barrelfish,kishoredbn/barrelfish,BarrelfishOS/barrelfish,BarrelfishOS/barrelfish,BarrelfishOS/barrelfish,BarrelfishOS/barrelfish,kishoredbn/barrelfish