sched/headers: Remove whitespace noise from kernel/sched/sched.h

A single case of space-Tab noise snuck in recently.

Fixes: 36569780 ("sched: Change nr_uninterruptible type to unsigned long")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://patch.msgid.link/176478595428.498.13816176784792752599.tip-bot2@tip-bot2