kconfig: require the argument of --defconfig

Currently, the argument for --defconfig is optional. If the argument
is not passed, the hard-coded default arch/$(ARCH)/defconfig is used.

It no longer happens in Linux since the last users of the default are
gone by the following commits:

- Commit f3e20ad67b ("s390: move arch/s390/defconfig to
  arch/s390/configs/defconfig")

- Commit 986a13769c ("alpha: move arch/alpha/defconfig to
  arch/alpha/configs/defconfig")

I want to kill the Linux-specific directory path embedded in the
Kconfig binary.

The --savedefconfig (reverse operation of --defconfig) requires an
argument, so it should not hurt to do likewise for --defconfig.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

scripts/kconfig/confdata.c

@@ -177,8 +177,6 @@ static void conf_message(const char *fmt, ...)
 static const char *conf_filename;
 static int conf_lineno, conf_warnings;
 
-const char conf_defname[] = "arch/$(ARCH)/defconfig";
-
 static void conf_warning(const char *fmt, ...)
 {
 	va_list ap;
@@ -233,21 +231,6 @@ static const char *conf_get_autoconfig_name(void)
 	return name ? name : "include/config/auto.conf";
 }
 
-char *conf_get_default_confname(void)
-{
-	static char fullname[PATH_MAX+1];
-	char *env, *name;
-
-	name = expand_string(conf_defname);
-	env = getenv(SRCTREE);
-	if (env) {
-		snprintf(fullname, sizeof(fullname), "%s/%s", env, name);
-		if (is_present(fullname))
-			return fullname;
-	}
-	return name;
-}
-
 static int conf_set_sym_val(struct symbol *sym, int def, int def_flags, char *p)
 {
 	char *p2;