[6.0] A value of cpu_shares can't be set by virsh correctly.

Issue

• A value of cpu_shares can't be set by virsh correctly. virsh's man page says that a valid value range is 0-262144 for cpu_shares.  Even if a valid value 0 or 1 is specified when "virsh schedinfo" is run, it changes the value to 2 unintentionally.
• In this case, "virsh schedinfo" shouldn't change the value, and should set the value as the specified one.  Our partner suspects that this behavior is due to a bug of "virsh schedinfo".