clang-tidy: Enable readability-convert-member-functions-to-static

This check finds non-static member functions that can be made
static because the functions don’t use this.
This check also triggers readability-static-accessed-through
-instance check as we are trying to access a static member
function through an instance.

Change-Id: I887b514a8478abedc24d5495d057b9d3e7dc9bdf
Signed-off-by: Pavithra Barithaya <pavithrabarithaya07@gmail.com>
diff --git a/.clang-tidy b/.clang-tidy
index f063ed1..0e5257a 100644
--- a/.clang-tidy
+++ b/.clang-tidy
@@ -245,6 +245,7 @@
 readability-avoid-const-params-in-decls,
 readability-braces-around-statements,
 readability-const-return-type,
+readability-convert-member-functions-to-static,
 readability-delete-null-pointer,
 readability-deleted-default,
 readability-function-size,