Add import_key entry point to p256-m driver

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
diff --git a/3rdparty/p256-m/p256-m_driver_entrypoints.h b/3rdparty/p256-m/p256-m_driver_entrypoints.h
index 18c677a..6eacbc3 100644
--- a/3rdparty/p256-m/p256-m_driver_entrypoints.h
+++ b/3rdparty/p256-m/p256-m_driver_entrypoints.h
@@ -29,6 +29,39 @@
 
 #include "psa/crypto_types.h"
 
+/** Import SECP256R1 key.
+ *
+ * \param[in]  attributes           The attributes of the key to use for the
+ *                                  operation.
+ * \param[in]  data                 The raw key material. For private keys
+ *                                  this must be a big-endian integer of 32
+ *                                  bytes; for public key this must be an
+ *                                  uncompressed ECPoint (65 bytes).
+ * \param[in]  data_length          The size of the raw key material.
+ * \param[out] key_buffer           The buffer to contain the key data in
+ *                                  output format upon successful return.
+ * \param[in]  key_buffer_size      Size of the \p key_buffer buffer in bytes.
+ * \param[out] key_buffer_length    The length of the data written in \p
+ *                                  key_buffer in bytes.
+ * \param[out] bits                 The bitsize of the key.
+ *
+ * \retval  #PSA_SUCCESS
+ *          Success. Keypair generated and stored in buffer.
+ * \retval  #PSA_ERROR_NOT_SUPPORTED
+ *          The input is not supported by this driver (not SECP256R1).
+ * \retval  #PSA_ERROR_INVALID_ARGUMENT
+ *          The input is invalid.
+ * \retval  #PSA_ERROR_BUFFER_TOO_SMALL
+ *          \p key_buffer_size is too small.
+ */
+psa_status_t p256_transparent_import_key(const psa_key_attributes_t *attributes,
+                             const uint8_t *data,
+                             size_t data_length,
+                             uint8_t *key_buffer,
+                             size_t key_buffer_size,
+                             size_t *key_buffer_length,
+                             size_t *bits);
+
 /** Generate SECP256R1 ECC Key Pair.
  *  Interface function which calls the p256-m key generation function and
  *  places it in the key buffer provided by the caller (mbed TLS) in the