Documentation: fix \p used for non-parameters

In Doxygen documentation, use \c rather than \p when discussing
something that isn't a parameter of the current macro or function.
Where needed, explain what the thing is.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/include/psa/crypto_se_driver.h b/include/psa/crypto_se_driver.h
index f5fe029..f6e3022 100644
--- a/include/psa/crypto_se_driver.h
+++ b/include/psa/crypto_se_driver.h
@@ -1061,7 +1061,8 @@
  * \brief A function that generates a symmetric or asymmetric key on a secure
  * element
  *
- * If \p type is asymmetric (#PSA_KEY_TYPE_IS_ASYMMETRIC(\p type) = 1),
+ * If the key type \c type recorded in \p attributes
+ * is asymmetric (#PSA_KEY_TYPE_IS_ASYMMETRIC(\c type) = 1),
  * the driver may export the public key at the time of generation,
  * in the format documented for psa_export_public_key() by writing it
  * to the \p pubkey buffer.