are referenced directly from ivar pointer. It's to do like what other
buses do. [1]
o changes exported prototypes. It doesn't use struct siba_* structures
anymore that instead of it it uses only device_t.
o removes duplicate code and debug messages.
o style(9)
Pointed out by: imp [1]
interface didn't be attached automatically at boot time so changes a
approach to attach children based on leveraging some newbus niceties.
Submitted by: nwhitehorn
