media: lirc: add missing exceptions for lirc uapi header file

Commit e5499dd7 ("media: lirc: revert removal of unused feature
flags") reintroduced unused feature flags in the lirc uapi header, but
failed to reintroduce the necessary exceptions for the docs.

Fixes: e5499dd7 ("media: lirc: revert removal of unused feature flags")
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>