Doc: fix doxygen comments.

Some existing doxygen comments resulted in bad or bad looking
documentation. These were fixed.

Change-Id: I20ab5a81c54d3bdc0e056965ad7de293d472cdf9
Signed-off-by: Gyorgy Szing <Gyorgy.Szing@arm.com>
diff --git a/interface/include/psa_client.h b/interface/include/psa_client.h
index 1fc8637..9fe25d9 100644
--- a/interface/include/psa_client.h
+++ b/interface/include/psa_client.h
@@ -96,7 +96,7 @@
  * \param[in] in_vec           Array of input \ref psa_invec structures
  * \param[in] in_len           Number of input \ref psa_invec structures
  * \param[in] out_vec          Array of input \ref psa_outvec structures
- * \param[in] in_len           Number of input \ref psa_outvec structures
+ * \param[in] out_len          Number of input \ref psa_outvec structures
  *
  * \retval >=0                 Application-specific return code
  * \retval <0                  Application-specific error code