(finally) fix #1099: return disklist correctly

in get_disks, when called with a parameter 'cciss/cXdY', we replaced
the '/' with '!' so that we can properly poll the information
about it from /sys/block/

but we have to replace the '!' with '/' again in our result list,
because the caller does not know anything about it and fails, because
the original dev is not in the list

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>

test/disk_tests/cciss/disklist_expected.json

@@ -1,5 +1,5 @@
 {
-    "cciss!c0d0" : {
+    "cciss/c0d0" : {
 	"wearout" : "N/A",
 	"vendor" : "HP",
 	"rpm" : -1,