Fix wrong \file name in Doxygen comments

Signed-off-by: Gilles Peskine <[email protected]>

library/md.c

@@ -1,5 +1,5 @@
 /**
- * \file mbedtls_md.c
+ * \file md.c
  *
  * \brief Generic message digest wrapper for mbed TLS
  *

tests/src/fake_external_rng_for_test.c

@@ -1,4 +1,4 @@
-/** \file psa_crypto_helpers.c
+/** \file fake_external_rng_for_test.c
  *
  * \brief Helper functions to test PSA crypto functionality.
  */