ovf: implement parsing out firmware type

it seems there is no part of the ovf standard that handles which type of
bios there is (at least i could not find it). Every ovf/ova i tested
either has no info about it, or has it in a vmware specific property
which we parse here.

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
Reviewed-by: Fiona Ebner <f.ebner@proxmox.com>

src/PVE/Storage/DirPlugin.pm

@@ -282,6 +282,11 @@ sub get_import_metadata {
 	};
     }
 
+    if (defined($res->{qm}->{bios}) && $res->{qm}->{bios} eq 'ovmf') {
+	$disks->{efidisk0} = 1;
+	push @$warnings, { type => 'efi-state-lost', key => 'bios', value => 'ovmf' };
+    }
+
     return {
 	type => 'vm',
 	source => $volname,