clang-tidy: Enable readability checks on repo

The readability-* checks in Clang-Tidy focus on improving code
readability by enforcing guidelines and suggesting improvements
that can enhance the clarity and maintainability of C++ code.
This enables readability-const-return-type check.

Signed-off-by: George Liu <liuxiwei@ieisystem.com>
Change-Id: I4253456bcab534ebf1c373988e0a1e5e6cfa1616
diff --git a/.clang-tidy b/.clang-tidy
index b9cb025..3e07c71 100644
--- a/.clang-tidy
+++ b/.clang-tidy
@@ -252,7 +252,26 @@
 performance-noexcept-move-constructor,
 performance-trivially-destructible,
 performance-type-promotion-in-math-fn,
-performance-unnecessary-copy-initialization'
+performance-unnecessary-copy-initialization,
+readability-delete-null-pointer,
+readability-deleted-default,
+readability-function-size,
+readability-identifier-naming,
+readability-isolate-declaration,
+readability-make-member-function-const,
+readability-misleading-indentation,
+readability-misplaced-array-index,
+readability-named-parameter,
+readability-non-const-parameter,
+readability-redundant-function-ptr-dereference,
+readability-redundant-preprocessor,
+readability-redundant-smartptr-get,
+readability-redundant-string-init,
+readability-simplify-subscript-expr,
+readability-static-definition-in-anonymous-namespace,
+readability-suspicious-call-argument,
+readability-uniqueptr-delete-release,
+readability-uppercase-literal-suffix'
 
 WarningsAsErrors: '*'
 HeaderFilterRegex: '.*.hpp'