conf: Remove nonsensical requirement of nvram format matching firmware format

conf: Remove nonsensical requirement of nvram format matching firmware format

The nvram image can have any supported format and there's no technical
requirement of them having the same format. In fact the actual nvram
image doesn't necessarily need to have the same format as the template
if the user is willing to format it themselves (as libvirt is not going
to convert it).

Remove the nonsensical check and adjust tests. The test case required
swapping around the format in order to work properly.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>