cleanse stack variable in kdf_pbkdf1_do_derive

cleanse stack variable in kdf_pbkdf1_do_derive

kdf_pbkdf1_do_derive stores key derivation information in a stack
variable, which is left uncleansed prior to returning.  Ensure that the
stack information is zeroed prior to return to avoid potential leaks of
key information

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/23194)