kconfig: do not hardcode ".config" filename

Rather than hardcoding ".config" use conf_get_configname(), which also
respects the environment variable KCONFIG_CONFIG.

This fixes "make silentoldconfig" when KCONFIG_CONFIG is used and also
suggests the given filename for "Load" and "Save as" in qconf.

Signed-off-by: Markus Heidelberg <markus.heidelberg@web.de>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
diff --git a/scripts/kconfig/qconf.cc b/scripts/kconfig/qconf.cc
index 19811fc..ce7d508 100644
--- a/scripts/kconfig/qconf.cc
+++ b/scripts/kconfig/qconf.cc
@@ -1448,7 +1448,7 @@
 
 void ConfigMainWindow::loadConfig(void)
 {
-	QString s = QFileDialog::getOpenFileName(".config", NULL, this);
+	QString s = QFileDialog::getOpenFileName(conf_get_configname(), NULL, this);
 	if (s.isNull())
 		return;
 	if (conf_read(QFile::encodeName(s)))
@@ -1464,7 +1464,7 @@
 
 void ConfigMainWindow::saveConfigAs(void)
 {
-	QString s = QFileDialog::getSaveFileName(".config", NULL, this);
+	QString s = QFileDialog::getSaveFileName(conf_get_configname(), NULL, this);
 	if (s.isNull())
 		return;
 	if (conf_write(QFile::encodeName(s)))