pk: remove duplicate define of MBEDTLS_PK_HAVE_ECC_KEYS

In pk.h, MBEDTLS_PK_HAVE_ECC_KEYS is enabled if ECP_C is defined or
USE_PSA_CRYPTO && PSA_WANT_KEY_TYPE_ECC_PUBLIC_KEY are defined.
But this logic is duplicate with its definition in
config_adjust_legacy_crypto.h.

Signed-off-by: Yanray Wang <yanray.wang@arm.com>
diff --git a/include/mbedtls/pk.h b/include/mbedtls/pk.h
index 66f3901..919543c 100644
--- a/include/mbedtls/pk.h
+++ b/include/mbedtls/pk.h
@@ -181,13 +181,6 @@
 #define MBEDTLS_PK_USE_PSA_EC_DATA
 #endif
 
-/* Helper symbol to state that the PK module has support for EC keys. This
- * can either be provided through the legacy ECP solution or through the
- * PSA friendly MBEDTLS_PK_USE_PSA_EC_DATA. */
-#if defined(MBEDTLS_PK_USE_PSA_EC_DATA) || defined(MBEDTLS_ECP_C)
-#define MBEDTLS_PK_HAVE_ECC_KEYS
-#endif /* MBEDTLS_PK_USE_PSA_EC_DATA || MBEDTLS_ECP_C */
-
 /**
  * \brief           Types for interfacing with the debug module
  */