Revert "build: add option to warn on recursive dependency"

This reverts commit 3204430e38.

Reverting this commit in preparation for reverting
dcf3e63a35 ("build: scripts/config - update to kconfig-v5.6") which
introduces various unaddressed build breakages.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

scripts/config/README

@@ -16,10 +16,6 @@ OpenWrt Buildroot:
  - reverted an upstream change that avoids writing symbols that are not
    visible to .config, which breaks OpenWrt busybox's '.config' generation
    logic.
- - add a compilation option (-DWARN_RECURSIVE_DEP) to treat recursive deps
-   as a warning, avoiding a complete build failure because of unrelated or
-   minor recursive deps, or making a scrict check before commiting a change
-   that may cause one.
  - use pre-built *.lex.c *.tab.[ch] files by default, to avoid depending on
    flex & bison.  Rebuild/remove these files only if running make with
    BUILD_SHIPPED_FILES defined

scripts/config/symbol.c

@@ -1250,11 +1250,6 @@ struct symbol *sym_check_deps(struct symbol *sym)
 		sym->flags &= ~SYMBOL_CHECK;
 	}
 
-#ifdef WARN_RECURSIVE_DEP
-	if (sym2 && sym2 == sym)
-		sym2 = NULL;
-#endif
-
 	return sym2;
 }