Keystore2: Fix some log messages.

Some multi line log messages were missing escape characters on their
line breaks.

Test: N/A
Change-Id: I3903b8a5ddd76d4e8ed379b3d42dc55942bbd98f
diff --git a/keystore2/src/maintenance.rs b/keystore2/src/maintenance.rs
index 9925e42..c0f1e1e 100644
--- a/keystore2/src/maintenance.rs
+++ b/keystore2/src/maintenance.rs
@@ -235,7 +235,7 @@
             }
             _ => {
                 return Err(Error::Rc(ResponseCode::INVALID_ARGUMENT)).context(
-                    "In migrate_key_namespace:
+                    "In migrate_key_namespace: \
                      Source domain must be one of APP, SELINUX, or KEY_ID.",
                 )
             }
@@ -249,7 +249,7 @@
             }
             _ => {
                 return Err(Error::Rc(ResponseCode::INVALID_ARGUMENT)).context(
-                    "In migrate_key_namespace:
+                    "In migrate_key_namespace: \
                      Destination domain must be one of APP or SELINUX.",
                 )
             }