Fixes minor typos in comments in pk.h and ctr_drbg.c

Fixes typos in PRs #475 and #437
diff --git a/include/mbedtls/pk.h b/include/mbedtls/pk.h
index 458bb51..f9f9b9b 100644
--- a/include/mbedtls/pk.h
+++ b/include/mbedtls/pk.h
@@ -496,11 +496,12 @@
  * \brief           Load and parse a public key
  *
  * \param ctx       key to be initialized
- * \param path      filename to read the private key from
+ * \param path      filename to read the public key from
  *
  * \note            On entry, ctx must be empty, either freshly initialised
- *                  with mbedtls_pk_init() or reset with mbedtls_pk_free(). If you need a
- *                  specific key type, check the result with mbedtls_pk_can_do().
+ *                  with mbedtls_pk_init() or reset with mbedtls_pk_free(). If
+ *                  you need a specific key type, check the result with
+ *                  mbedtls_pk_can_do().
  *
  * \note            The key is also checked for correctness.
  *
diff --git a/library/ctr_drbg.c b/library/ctr_drbg.c
index aefddfa..6962d68 100644
--- a/library/ctr_drbg.c
+++ b/library/ctr_drbg.c
@@ -67,7 +67,7 @@
 }
 
 /*
- * Non-public function wrapped by ctr_crbg_init(). Necessary to allow NIST
+ * Non-public function wrapped by mbedtls_ctr_drbg_init(). Necessary to allow NIST
  * tests to succeed (which require known length fixed entropy)
  */
 int mbedtls_ctr_drbg_seed_entropy_len(