ble: update sdkconfig.defaults.esp32c6 file for blufi example

examples/bluetooth/blufi/sdkconfig.defaults.esp32c6

@@ -9,5 +9,10 @@ CONFIG_BT_NIMBLE_BLUFI_ENABLE=y
 # CONFIG_BT_BLE_50_FEATURES_SUPPORTED is not set
 CONFIG_BT_BLE_42_FEATURES_SUPPORTED=y
 CONFIG_MBEDTLS_DHM_C=y
+# The config items for NIMBLE HOST
 CONFIG_BT_NIMBLE_ENABLED=y
+CONFIG_BT_NIMBLE_ROLE_CENTRAL=n
+CONFIG_BT_NIMBLE_ROLE_OBSERVER=n
 CONFIG_BT_NIMBLE_50_FEATURE_SUPPORT=n
+CONFIG_BT_NIMBLE_SECURITY_ENABLE=n
+CONFIG_BT_NIMBLE_CRYPTO_STACK_MBEDTLS=n