feature-removal-schedule: remove SA_* flags entry

No reason to keep the feature-removal-schedule.txt entry after the code
was removed.

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>