Merge branch 'bugfix/fix_ble_examples' into 'master'

examples/bluetooth: Miscellaneous fixes in some of the examples

See merge request idf/esp-idf!3549

diff --cc examples/bluetooth/gatt_security_server/main/example_ble_sec_gatts_demo.c
Simple merge

diff --cc examples/bluetooth/gatt_server/main/gatts_demo.c
Simple merge

diff --cc examples/bluetooth/gatt_server_service_table/main/gatts_table_creat_demo.c
Simple merge