spvm: Format all disks before the test starts

lib/bootloader_pvm.pm

@@ -117,10 +117,15 @@ sub prepare_pvm_installation {
 
     # Delete partition table before starting installation
     select_console('install-shell');
-    foreach my $disk (split(',', get_var('DISK_DEVICES', 'sda'))) {
-        script_run("wipefs -a /dev/$disk");
+
+    # first disk is always sda
+    my $dev_id = 'a';
+    foreach my $n (1 .. get_var('NUMDISKS', 1)) {
+        script_run("wipefs -a /dev/sd$dev_id");
         # For cryptlvm+activate existing scenario, create empty enrypted partition
-        create_encrypted_part("$disk") if get_var('ENCRYPT_ACTIVATE_EXISTING');
+        create_encrypted_part("sd$dev_id") if get_var('ENCRYPT_ACTIVATE_EXISTING');
+        # apply next letter as dev_id as we assume that they are just incremented
+        $dev_id = chr((ord $dev_id) + 1);
     }
     # Switch to installation console (ssh or vnc)
     select_console('installation');