bss: fix missing config bss_no_flush_when_down

This is Android-specific feature to avoid removing bss on interface
down.

This config is removed unexpectedly in last upstream merge.

Bug: 128935493
Test: manually switch between two access points
Change-Id: I718d375f189d2e3bc974f40382c45c48f1d7707c
diff --git a/wpa_supplicant/config.c b/wpa_supplicant/config.c
index 2902413..839dea2 100644
--- a/wpa_supplicant/config.c
+++ b/wpa_supplicant/config.c
@@ -4862,6 +4862,7 @@
 	{ INT_RANGE(gas_rand_mac_addr, 0, 2), 0 },
 	{ INT_RANGE(dpp_config_processing, 0, 2), 0 },
 	{ INT_RANGE(coloc_intf_reporting, 0, 1), 0 },
+	{ INT_RANGE(bss_no_flush_when_down, 0, 1), 0 },
 };
 
 #undef FUNC