Rename ssl_internal.h to ssl_misc.h

Signed-off-by: Chris Jones <christopher.jones@arm.com>
diff --git a/library/ssl_cache.c b/library/ssl_cache.c
index 141c480..bb5007b 100644
--- a/library/ssl_cache.c
+++ b/library/ssl_cache.c
@@ -34,7 +34,7 @@
 #endif
 
 #include "mbedtls/ssl_cache.h"
-#include "ssl_internal.h"
+#include "ssl_misc.h"
 
 #include <string.h>