custom theme: Fix the install custom theme

Change-Id: I639bfdac46cbe5a0d9760d1b62fd5f9875b63994
diff --git a/twrpinstall/twinstall.cpp b/twrpinstall/twinstall.cpp
index e1f8415..7975a97 100755
--- a/twrpinstall/twinstall.cpp
+++ b/twrpinstall/twinstall.cpp
@@ -354,7 +354,7 @@
 		} else {
 			std::string binary_name("ui.xml");
 			ZipEntry64 binary_entry;
-			if (FindEntry(Zip, binary_name, &binary_entry) != 0) {
+			if (FindEntry(Zip, binary_name, &binary_entry) == 0) {
 				LOGINFO("TWRP theme zip\n");
 				ret_val = Install_Theme(path, Zip);
 			} else {