m4/virt-loader-nvram: use quotation for list of loader:nvram pairs
m4/virt-loader-nvram: use quotation for list of loader:nvram pairs

The bug was introduced by commit 08c2d1480b.  The string must be quoted
because it is used as function argument.

Signed-off-by: Pavel Hrdina <d4772d05997b8abf035041e3b4f4996380ea7e7a@redhat.com>

crobinso/libvirt,crobinso/libvirt,taget/libvirt,zippy2/libvirt,VenkatDatta/libvirt,jardasgit/libvirt,zippy2/libvirt,olafhering/libvirt,eskultety/libvirt,andreabolognani/libvirt,fabianfreyer/libvirt,fabianfreyer/libvirt,jardasgit/libvirt,taget/libvirt,jardasgit/libvirt,fabianfreyer/libvirt,olafhering/libvirt,taget/libvirt,datto/libvirt,datto/libvirt,jfehlig/libvirt,taget/libvirt,crobinso/libvirt,andreabolognani/libvirt,nertpinx/libvirt,jardasgit/libvirt,nertpinx/libvirt,zippy2/libvirt,VenkatDatta/libvirt,jfehlig/libvirt,datto/libvirt,VenkatDatta/libvirt,nertpinx/libvirt,nertpinx/libvirt,eskultety/libvirt,VenkatDatta/libvirt,jardasgit/libvirt,eskultety/libvirt,fabianfreyer/libvirt,olafhering/libvirt,jfehlig/libvirt,andreabolognani/libvirt,olafhering/libvirt,eskultety/libvirt,nertpinx/libvirt,jfehlig/libvirt,andreabolognani/libvirt,libvirt/libvirt,libvirt/libvirt,zippy2/libvirt,fabianfreyer/libvirt,andreabolognani/libvirt,libvirt/libvirt,VenkatDatta/libvirt,datto/libvirt,datto/libvirt,crobinso/libvirt,taget/libvirt,eskultety/libvirt,libvirt/libvirt