handle fresh setup with mixed drives (#10273)

fresh drive setups when one of the drive is
a root drive, we should ignore such a root
drive and not proceed to format.

This PR handles this properly by marking
the disks which are root disk and they are
taken offline.

cmd/storage-interface.go

@@ -29,6 +29,7 @@ type StorageAPI interface {
 	// Storage operations.
 	IsOnline() bool // Returns true if disk is online.
 	IsLocal() bool
+
 	Hostname() string // Returns host name if remote host.
 	Close() error
 	GetDiskID() (string, error)