remove prototypes with no matching function
ok mpi@

spelling
feedback and ok tb@ jmc@ ok ratchov@

Constify struct cfattach.

ok visa@ a long time ago, ok patrick@

Add amldwusb(4), amlusbphy(4) and amlpciephy(4), drivers for the USB
controller glue and USB PHYs found on the Amlogic G12A/B SoCs.

ok patrick@