zvm plugin doesn't require specific kernel modules "vmcp" and "cpint" to execute propelry

Description of problem:

See PR https://github.com/sosreport/sos/pull/3238.
These modules just do not exist on RHEL8 and hence are not required to execute "vmcp" commands.

Version-Release number of selected component (if applicable):

sos-4.3-5.el8.noarch

How reproducible:

Always

Steps to Reproduce:
1. Execute "sos -o zvm" on a s390x system

Actual results:

All "vmcp" commands skipped:

[plugin:zvm] skipped command 'vmcp q userid':
[plugin:zvm] skipped command 'vmcp q userid': required kmods missing: cpint, vmcp.
[plugin:zvm] skipped command 'vmcp q users': required kmods missing: cpint, vmcp.
[plugin:zvm] skipped command 'vmcp q privclass': required kmods missing: cpint, vmcp.
...

Expected results:

"vmcp" commands executing