doxygen: fix parameter name typos and misused \p commands

\p is reserved for function parameters.
\c is used to describe other values and variables.
Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>
diff --git a/include/mbedtls/rsa.h b/include/mbedtls/rsa.h
index f8725ff..a1d0c16 100644
--- a/include/mbedtls/rsa.h
+++ b/include/mbedtls/rsa.h
@@ -537,7 +537,7 @@
  * \note           This function does not handle message padding.
  *
  * \note           Make sure to set \p input[0] = 0 or ensure that
- *                 input is smaller than \p N.
+ *                 input is smaller than \c N.
  *
  * \return         \c 0 on success.
  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
@@ -1109,8 +1109,8 @@
  *                 verification using the mode from the context.
  *
  * \note           For PKCS#1 v2.1 encoding, see comments on
- *                 mbedtls_rsa_rsassa_pss_verify() about \p md_alg and
- *                 \p hash_id.
+ *                 mbedtls_rsa_rsassa_pss_verify() about \c md_alg and
+ *                 \c hash_id.
  *
  * \deprecated     It is deprecated and discouraged to call this function
  *                 in #MBEDTLS_RSA_PRIVATE mode. Future versions of the library