KEYS: trusted: tpm2: Fix migratable logic

KEYS: trusted: tpm2: Fix migratable logic

When creating (sealing) a new trusted key, migratable
trusted keys have the FIXED_TPM and FIXED_PARENT attributes
set, and non-migratable keys don't. This is backwards, and
also causes creation to fail when creating a migratable key
under a migratable parent. (The TPM thinks you are trying to
seal a non-migratable blob under a migratable parent.)

The following simple patch fixes the logic, and has been
tested for all four combinations of migratable and non-migratable
trusted keys and parent storage keys. With this logic, you will
get a proper failure if you try to create a non-migratable
trusted key under a migratable parent storage key, and all other
combinations work correctly.

Cc: stable@vger.kernel.org # v5.13+
Fixes: e5fb5d2c5a03 ("security: keys: trusted: Make sealed key properly interoperable")
Signed-off-by: David Safford <david.safford@gmail.com>
Reviewed-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>