nvs_flash: Add support for HMAC-based NVS encryption keys protection scheme

- This features allows the NVS encryption keys to be derived and protected using
  the HMAC peripheral. Since the encryption keys are derived at runtime, they
  are not stored anywhere in the flash and hence this feature does not require
  a separate `nvs_keys` partition.

components/nvs_flash/src/nvs_partition_manager.cpp

@@ -8,9 +8,9 @@
 #include "nvs_partition_lookup.hpp"
 #include "nvs_internal.h"
 
-#ifdef CONFIG_NVS_ENCRYPTION
+#ifndef LINUX_TARGET
 #include "nvs_encrypted_partition.hpp"
-#endif // CONFIG_NVS_ENCRYPTION
+#endif // ! LINUX_TARGET
 
 namespace nvs {
 
@@ -100,7 +100,6 @@ esp_err_t NVSPartitionManager::init_custom(Partition *partition, uint32_t baseSe
     return err;
 }
 
-#ifdef CONFIG_NVS_ENCRYPTION
 #ifdef ESP_PLATFORM
 esp_err_t NVSPartitionManager::secure_init_partition(const char *part_name, nvs_sec_cfg_t* cfg)
 {
@@ -140,7 +139,6 @@ esp_err_t NVSPartitionManager::secure_init_partition(const char *part_name, nvs_
     return ESP_OK;
 }
 #endif // ESP_PLATFORM
-#endif // CONFIG_NVS_ENCRYPTION
 
 esp_err_t NVSPartitionManager::deinit_partition(const char *partition_label)
 {