Using the *_MASK defines for "maximal value" is debatable. I got the
idea from FreeBSD, and it sorta makes sense to me.

Some hunks look a bit incomplete, because code that is going to be
subsequently removed is not touched here.
Signed-off-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
Link: https://lore.kernel.org/r/20230428080732.1697695-1-oswald.buddenhagen@gmx.deSigned-off-by: Takashi Iwai <tiwai@suse.de>