Use consistent guards for deprecated feature

Fixes an "unused static function" warning in builds with
DEPRECATED_REMOVED.

While at it, remove an include that's now useless.

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
diff --git a/include/mbedtls/cipher.h b/include/mbedtls/cipher.h
index de3de8a..03e2327 100644
--- a/include/mbedtls/cipher.h
+++ b/include/mbedtls/cipher.h
@@ -366,7 +366,7 @@
     mbedtls_cmac_context_t *MBEDTLS_PRIVATE(cmac_ctx);
 #endif
 
-#if defined(MBEDTLS_USE_PSA_CRYPTO)
+#if defined(MBEDTLS_USE_PSA_CRYPTO) && !defined(MBEDTLS_DEPRECATED_REMOVED)
     /** Indicates whether the cipher operations should be performed
      *  by Mbed TLS' own crypto library or an external implementation
      *  of the PSA Crypto API.
@@ -375,7 +375,7 @@
      *  mbedtls_cipher_setup_psa().
      */
     unsigned char MBEDTLS_PRIVATE(psa_enabled);
-#endif /* MBEDTLS_USE_PSA_CRYPTO */
+#endif /* MBEDTLS_USE_PSA_CRYPTO && !MBEDTLS_DEPRECATED_REMOVED */
 
 } mbedtls_cipher_context_t;