Fixed various typos

Signed-off-by: Deepak Kathayat <deepak.mk17@gmail.com>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
diff --git a/block/qcow.c b/block/qcow.c
index 1e128be..d5a7d5f 100644
--- a/block/qcow.c
+++ b/block/qcow.c
@@ -723,7 +723,7 @@
             backing_file = NULL;
         }
         header.cluster_bits = 9; /* 512 byte cluster to avoid copying
-                                    unmodifyed sectors */
+                                    unmodified sectors */
         header.l2_bits = 12; /* 32 KB L2 tables */
     } else {
         header.cluster_bits = 12; /* 4 KB clusters */