x86/msr: Correct the emulation behaviour of MSR_PRED_CMD

x86/msr: Correct the emulation behaviour of MSR_PRED_CMD

Experimentally, the behaviour of reserved bits in MSR_PRED_CMD changed between
beta and production microcode, and now raises a #GP fault for set reserved
bits.  The AMD spec for future hardware also specifies this behaviour, and it
is the more sensible behaviour to implement.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Release-acked-by: Juergen Gross <jgross@suse.com>