Move the inclusion of crypto_spe.h to psa/crypto_platform.h

This makes it easier to ensure that crypto_spe.h is included everywhere it
needs to be, and that it's included early enough to do its job (it must be
included before any mention of psa_xxx() functions with external linkage,
because it defines macros to rename these functions).

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/include/psa/crypto_platform.h b/include/psa/crypto_platform.h
index 8acf22c..66f4687 100644
--- a/include/psa/crypto_platform.h
+++ b/include/psa/crypto_platform.h
@@ -81,6 +81,18 @@
 
 #endif /* MBEDTLS_PSA_CRYPTO_KEY_ID_ENCODES_OWNER */
 
+/*
+ * When MBEDTLS_PSA_CRYPTO_SPM is defined, the code is being built for SPM
+ * (Secure Partition Manager) integration which separates the code into two
+ * parts: NSPE (Non-Secure Processing Environment) and SPE (Secure Processing
+ * Environment). When building for the SPE, an additional header file should be
+ * included.
+ */
+#if defined(MBEDTLS_PSA_CRYPTO_SPM)
+#define PSA_CRYPTO_SECURE 1
+#include "crypto_spe.h"
+#endif // MBEDTLS_PSA_CRYPTO_SPM
+
 #if defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG)
 /** The type of the context passed to mbedtls_psa_external_get_random().
  *