sched/headers: Remove #include <linux/capability.h> from <linux/sched.h>

The <linux/sched.h> header does not actually make use of any
types or APIs defined in <linux/capability.h>, so remove its inclusion.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>