nrf_security: remove mbedtls/platform.h

We have been duplicating this file from Mbed TLS, and I don't like
duplication.
Instead define MBEDTLS_PLATFORM_NO_STD_FUNCTIONS when building
the crypto library so that it doesn't link against problematic
libc functions.
If it turns out to be too much then we can individually replace
the calloc and free functions with the appropriate macros.

Signed-off-by: Tomi Fontanilles <tomi.fontanilles@nordicsemi.no>

Author: tomi-font

subsys/nrf_security/Kconfig.tf-psa-crypto

@@ -10,6 +10,10 @@ configdefault TF_PSA_CRYPTO_CONFIG_FILE
 configdefault TF_PSA_CRYPTO_USER_CONFIG_FILE
 	default "nrf-psa-crypto-user-config.h"
 
+# Prevent TF-PSA-Crypto from linking against calloc() and free().
+config MBEDTLS_PLATFORM_NO_STD_FUNCTIONS
+	default y
+
 # Make sure that MBEDTLS_PSA_CRYPTO_RNG_SOURCE is available even when !MBEDTLS_PSA_CRYPTO_C
 # (when building TF-M) so that MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG is always enabled.
 # This is needed because without this symbol the Oberon PSA core defaults to legacy RNG.

subsys/nrf_security/cmake/psa_crypto_config.cmake

@@ -17,6 +17,7 @@ kconfig_check_and_set_base_int(MBEDTLS_PSA_KEY_SLOT_COUNT)
 # Platform
 kconfig_check_and_set_base(MBEDTLS_PLATFORM_C)
 kconfig_check_and_set_base(MBEDTLS_PLATFORM_MEMORY)
+kconfig_check_and_set_base(MBEDTLS_PLATFORM_NO_STD_FUNCTIONS)
 kconfig_check_and_set_base(MBEDTLS_MEMORY_BUFFER_ALLOC_C)
 
 # TF-M

subsys/nrf_security/configs/psa_crypto_config.h.template

@@ -20,6 +20,7 @@
 /* Platform */
 #cmakedefine MBEDTLS_PLATFORM_C
 #cmakedefine MBEDTLS_PLATFORM_MEMORY
+#cmakedefine MBEDTLS_PLATFORM_NO_STD_FUNCTIONS
 #cmakedefine MBEDTLS_MEMORY_BUFFER_ALLOC_C
 
 /* TF-M */