Revert "build: config: allow bool to select a module pkg"

This reverts commit 8514b6b42c.

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

@@ -22,9 +22,7 @@ OpenWrt Buildroot:
    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.
- - allow a bool symbol to select a tristate symbol that depends on m (i.e.
-   a package that should only be built as a module).
+   BUILD_SHIPPED_FILES defined
 
 For a full list of changes, see the repository at:
 https://github.com/cotequeiroz/linux/commits/openwrt/scripts/kconfig

scripts/config/symbol.c

@@ -205,7 +205,7 @@ static void sym_calc_visibility(struct symbol *sym)
 	tri = yes;
 	if (sym->dir_dep.expr)
 		tri = expr_calc_value(sym->dir_dep.expr);
-	if (tri == mod)
+	if (tri == mod && sym_get_type(sym) == S_BOOLEAN)
 		tri = yes;
 	if (sym->dir_dep.tri != tri) {
 		sym->dir_dep.tri = tri;