x86/amd: protect set_cpuidmask() against #GP faults

x86/amd: protect set_cpuidmask() against #GP faults

Virtual environments such as Xen HVM containers and VirtualBox do not
necessarily provide support for feature masking MSRs.

As their presence is detected by model numbers alone, and their use predicated
on command line parameters, use the safe() variants of {wr,rd}msr() to avoid
dying with an early #GP fault.

In fact, use the password variants in all cases because:
    a) they are safe to use even if not strictly required
    b) have a more useful function prototype for this purposes

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>