ima: Finish deprecation of IMA_TRUSTED_KEYRING Kconfig
The removal of IMA_TRUSTED_KEYRING made IMA_LOAD_X509
and IMA_BLACKLIST_KEYRING unavailable because the latter
two depend on the former. Since IMA_TRUSTED_KEYRING was
deprecated in favor of INTEGRITY_TRUSTED_KEYRING use it
as a dependency for the two Kconfigs affected by the
deprecation.