Missing UpdateState::Cancelled string conversions

Add the missing UpdateState::Cancelled conversions from/to string.

Bug: none
Test: build
Change-Id: I097d80e21521725fbb02f3ef37b22e95a5e83929
Signed-off-by: Alessio Balsini <balsini@google.com>
diff --git a/fs_mgr/libsnapshot/snapshot.cpp b/fs_mgr/libsnapshot/snapshot.cpp
index 785882a..a6f07fc 100644
--- a/fs_mgr/libsnapshot/snapshot.cpp
+++ b/fs_mgr/libsnapshot/snapshot.cpp
@@ -1709,6 +1709,8 @@
         return UpdateState::MergeNeedsReboot;
     } else if (contents == "merge-failed") {
         return UpdateState::MergeFailed;
+    } else if (contents == "cancelled") {
+        return UpdateState::Cancelled;
     } else {
         LOG(ERROR) << "Unknown merge state in update state file: \"" << contents << "\"";
         return UpdateState::None;
@@ -1731,6 +1733,8 @@
             return os << "merge-needs-reboot";
         case UpdateState::MergeFailed:
             return os << "merge-failed";
+        case UpdateState::Cancelled:
+            return os << "cancelled";
         default:
             LOG(ERROR) << "Unknown update state: " << static_cast<uint32_t>(state);
             return os;