keystore2: factor out create_super_key()

Currently the UnlockedDeviceRequired super keys are created by
get_or_create_super_key(), while the AfterFirstUnlock super key is
created by separate code in init_user().  The super key creation code in
get_or_create_super_key() is generic enough to work for all super keys,
however.  This CL factors this code out into a new function
create_super_key(), which a later CL will use for the AfterFirstUnlock
super key.  No change in behavior.

Bug: 296464083
Test: atest -p --include-subdirs system/security/keystore2
Flag: exempt, mechanical refactoring
Change-Id: I88779273efef6cb925152381c07549e1f49daecf
1 file changed