Fix some copypasta in references to parameter names

Validated by

perl -ne 'if (/^\/\*\*/) {%param=(); @p=()} if (/\\param.*? (\w+)/) {$param{$1}=1} while (/\\p \*?(\w+)/g) {push @p,[$1,ARGV->input_line_number()]} if (/^\ \*\//) {foreach (@p) {if (!$param{$_->[0]}) {printf "%s:%d: bad \\p %s\n", $ARGV, $_->[1], $_->[0]}}} close ARGV if eof' include/psa/*.h
diff --git a/include/psa/crypto_extra.h b/include/psa/crypto_extra.h
index a0eac4d..d14edd9 100644
--- a/include/psa/crypto_extra.h
+++ b/include/psa/crypto_extra.h
@@ -125,7 +125,7 @@
  * FIMXE This function is no longer part of the official API. Its prototype
  * is only kept around for the sake of tests that haven't been updated yet.
  *
- * A key derivation algorithm takes three inputs: a secret input \p key and
+ * A key derivation algorithm takes three inputs: a secret input \p handle and
  * two non-secret inputs \p label and p salt.
  * The result of this function is a byte generator which can
  * be used to produce keys and other cryptographic material.