rules: install modules-load file for msr module load

libvirt needs to access MSRs to detect some features (vmx-* for Intel CPUs) in recent x86 CPUs. This access is done via /dev/cpu/*/msr that are populated and managed by the msr kernel module.

The msr module is not loaded by default, as a consequence, libvirt is unable to detect some features and to detect the right Host CPU model. Request msr module load at package install and boot fixes this issue.