MAINTAINERS: fix email address for Lisa Liu

There was a small typographical error which resulted in an
email address which does not exist in Gerrit.  s/lui/liu

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I53494c869c6f1124dbdc4c70160eb966b13969e3
diff --git a/MAINTAINERS b/MAINTAINERS
index db50e29..21fe75e 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -43,4 +43,4 @@
 -------------------------
 
 M:  Benjamin Fair <benjaminfair@google.com> <benjaminfair!>
-M:  Lisa Liu <luiyj19@lenovo.com>
+M:  Lisa Liu <liuyj19@lenovo.com>