Otapreopt: Fix count

Don't count null for argc.

Bug: 37158297
Test: m
Test: OTA pre-versioned -> OTA versioned
Change-Id: I378b0b7b445f34c766460182d724d6abd84ff773
diff --git a/cmds/installd/otapreopt.cpp b/cmds/installd/otapreopt.cpp
index ae4c797..ff838ce 100644
--- a/cmds/installd/otapreopt.cpp
+++ b/cmds/installd/otapreopt.cpp
@@ -313,8 +313,7 @@
                                         + 1   // filter
                                         + 1   // volume
                                         + 1   // libs
-                                        + 1   // seinfo
-                                        + 1;  // null
+                                        + 1;  // seinfo
             if (argc == kV2ArgCount) {
                 return ReadArgumentsV2(argc, argv, false);
             } else {