spi_flash: remove duplicate definition of spi_flash_unlock

The other (static) definition is in flash_ops.c, all references are
also in flash_ops.c.

examples/security/flash_encryption/example_test.py

@@ -0,0 +1,41 @@
+from __future__ import print_function
+import os
+import sys
+
+try:
+    import IDF
+except ImportError:
+    test_fw_path = os.getenv('TEST_FW_PATH')
+    if test_fw_path and test_fw_path not in sys.path:
+        sys.path.insert(0, test_fw_path)
+    import IDF
+
+
+# To prepare a test runner for this example:
+# 1. Generate zero flash encryption key:
+#   dd if=/dev/zero of=key.bin bs=1 count=32
+# 2.Burn Efuses:
+#   espefuse.py --do-not-confirm -p $ESPPORT burn_efuse FLASH_CRYPT_CONFIG 0xf
+#   espefuse.py --do-not-confirm -p $ESPPORT burn_efuse FLASH_CRYPT_CNT 0x1
+#   espefuse.py --do-not-confirm -p $ESPPORT burn_key flash_encryption key.bin
+@IDF.idf_example_test(env_tag='Example_Flash_Encryption')
+def test_examples_security_flash_encryption(env, extra_data):
+    dut = env.get_dut('flash_encryption', 'examples/security/flash_encryption')
+    # start test
+    dut.start_app()
+    lines = [
+        'FLASH_CRYPT_CNT eFuse value is 1',
+        'Flash encryption feature is enabled in DEVELOPMENT mode',
+        'with esp_partition_write',
+        '00 01 02 03 04 05 06 07  08 09 0a 0b 0c 0d 0e 0f',
+        'with esp_partition_read',
+        '00 01 02 03 04 05 06 07  08 09 0a 0b 0c 0d 0e 0f',
+        'with spi_flash_read',
+        '29 68 2e 13 88 a0 5b 7f  cc 6b 39 f9 d7 7b 32 2f'
+    ]
+    for line in lines:
+        dut.expect(line, timeout=2)
+
+
+if __name__ == '__main__':
+    test_examples_security_flash_encryption()