KEYS: trusted: Rollback init_trusted() consistently

Do bind neither static calls nor trusted_key_exit() before a successful
init, in order to maintain a consistent state. In addition, depart the
init_trusted() in the case of a real error (i.e. getting back something
else than -ENODEV).

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Closes: https://lore.kernel.org/linux-integrity/CAHk-=whOPoLaWM8S8GgoOPT7a2+nMH5h3TLKtn=R_3w4R1_Uvg@mail.gmail.com/


Cc: stable@vger.kernel.org # v5.13+
Fixes: 5d0682be ("KEYS: trusted: Add generic trusted keys framework")
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>