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/camellia.h b/include/mbedtls/camellia.h
index 05397d2..b136fd2 100644
--- a/include/mbedtls/camellia.h
+++ b/include/mbedtls/camellia.h
@@ -231,7 +231,7 @@
  * *note       Due to the nature of CTR mode, you should use the same
  *             key for both encryption and decryption. In particular, calls
  *             to this function should be preceded by a key-schedule via
- *             mbedtls_camellia_setkey_enc() regardless of whether \p mode
+ *             mbedtls_camellia_setkey_enc() regardless of whether \c mode
  *             is #MBEDTLS_CAMELLIA_ENCRYPT or #MBEDTLS_CAMELLIA_DECRYPT.
  *
  * \warning    You must never reuse a nonce value with the same key. Doing so