edify: Remove VAL_INVALID and move ValueType into Value class.

Test: mmma -j bootable/recovery
Test: Run recovery_component_test and recovery_unit_test on marlin.
Change-Id: I4b240e3e771c387b9694be9c0f2f74e0265ab4cb
diff --git a/edify/expr.cpp b/edify/expr.cpp
index 6823b73..c090eb2 100644
--- a/edify/expr.cpp
+++ b/edify/expr.cpp
@@ -51,9 +51,9 @@
     if (!v) {
         return false;
     }
-    if (v->type != VAL_STRING) {
-        ErrorAbort(state, kArgsParsingFailure, "expecting string, got value type %d", v->type);
-        return false;
+    if (v->type != Value::Type::STRING) {
+      ErrorAbort(state, kArgsParsingFailure, "expecting string, got value type %d", v->type);
+      return false;
     }
 
     *result = v->data;
@@ -68,7 +68,7 @@
     if (str == nullptr) {
         return nullptr;
     }
-    return new Value(VAL_STRING, str);
+    return new Value(Value::Type::STRING, str);
 }
 
 Value* StringValue(const std::string& str) {