pvs args shall be submitted as a list

pvs args are submitted as a string to vgcreate, but the run_command
expects a list however. This caused problem for multiple args.

This is a fix for https://github.com/ansible/ansible/issues/8316 (reported in the old main ansible repo - before ansible decided to split main repo into two repos.)

The issue caused ansible to fail to iterate over multiple pvs ars. E.g:

lvg: vg=new_vg pvs=/dev/sdb1,/dev/sdc1 vg_options=""