py: Remove unnecessary BINARY_OP_EQUAL code that just checks pointers.

Previous patch c38dc3ccc76d1a9bf867704f43ea5d15da3fea7b allowed any
object to be compared with any other, using pointer comparison for a
fallback.  As such, existing code which checked for this case is no
longer needed.
diff --git a/py/objstr.c b/py/objstr.c
index 688988c..01ed3a2 100644
--- a/py/objstr.c
+++ b/py/objstr.c
@@ -348,16 +348,12 @@
     } else if (lhs_type == &mp_type_bytes) {
         mp_buffer_info_t bufinfo;
         if (!mp_get_buffer(rhs_in, &bufinfo, MP_BUFFER_READ)) {
-            goto incompatible;
+            return MP_OBJ_NULL; // op not supported
         }
         rhs_data = bufinfo.buf;
         rhs_len = bufinfo.len;
     } else {
         // incompatible types
-    incompatible:
-        if (op == MP_BINARY_OP_EQUAL) {
-            return mp_const_false; // can check for equality against every type
-        }
         return MP_OBJ_NULL; // op not supported
     }