kconfig: remove unused code for S_DEF_AUTO in conf_read_simple()

The 'else' arm here is unreachable in practical use cases.

include/config/auto.conf does not include "# CONFIG_... is not set"
line unless it is manually hacked.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

scripts/kconfig/confdata.c

@@ -436,20 +436,15 @@ int conf_read_simple(const char *name, int def)
 			*p++ = 0;
 			if (strncmp(p, "is not set", 10))
 				continue;
-			if (def == S_DEF_USER) {
-				sym = sym_find(line + 2 + strlen(CONFIG_));
-				if (!sym) {
-					if (warn_unknown)
-						conf_warning("unknown symbol: %s",
-							     line + 2 + strlen(CONFIG_));
 
-					conf_set_changed(true);
-					continue;
-				}
-			} else {
-				sym = sym_lookup(line + 2 + strlen(CONFIG_), 0);
-				if (sym->type == S_UNKNOWN)
-					sym->type = S_BOOLEAN;
+			sym = sym_find(line + 2 + strlen(CONFIG_));
+			if (!sym) {
+				if (warn_unknown)
+					conf_warning("unknown symbol: %s",
+						     line + 2 + strlen(CONFIG_));
+
+				conf_set_changed(true);
+				continue;
 			}
 			if (sym->flags & def_flags) {
 				conf_warning("override: reassigning to symbol %s", sym->name);