comps: mark kernel-qubes-vm as required regardless of template rpms

Currently kernel-qubes-vm is pulled in by template rpms. Since dnf
automatically remove "unneeded" packages, it would also remove
kernel-qubes-vm with the last template rpm (which isn't necessary last
template in general). To prevent this, install kernel-qubes-vm
regardless of templates.

Fixes QubesOS/qubes-issues#2107

conf/comps-qubes.xml

@@ -1154,6 +1154,7 @@
     <uservisible>false</uservisible>
     <packagelist>
       <packagereq type="mandatory">kernel</packagereq>
+      <packagereq type="mandatory">kernel-qubes-vm</packagereq>
       <packagereq type="mandatory">qubes-core-dom0</packagereq>
       <packagereq type="mandatory">qubes-core-dom0-doc</packagereq>
       <packagereq type="mandatory">qubes-gui-dom0</packagereq>