Make legacy_or_psa.h public.

As a public header, it should no longer include common.h, just use
build_info.h which is what we actually need anyway.

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
diff --git a/library/ssl_misc.h b/library/ssl_misc.h
index a59e672..edbf446 100644
--- a/library/ssl_misc.h
+++ b/library/ssl_misc.h
@@ -32,7 +32,7 @@
 #include "mbedtls/psa_util.h"
 #include "hash_info.h"
 #endif
-#include "legacy_or_psa.h"
+#include "mbedtls/legacy_or_psa.h"
 
 #if defined(MBEDTLS_MD5_C)
 #include "mbedtls/md5.h"