It makes sense to do the length checking in the core rather than expect
each driver to deal with it themselves. This puts the onus on the core to
dictate which algorithm/key combinations are valid before calling a driver.
Additionally, this commit also updates the psa_mac_sign_finish function
to better deal with output buffer sanitation, as per the review comments
on #4247.
Signed-off-by: Steven Cooreman <steven.cooreman@silabs.com>