sched/deadline: Clarify nanoseconds in uapi

Specify the time values of the deadline parameters of deadline,
runtime, and period as being in nanoseconds explicitly as they always
have been.
Signed-off-by: Christian Loehle <christian.loehle@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Link: https://lore.kernel.org/r/20240813144348.1180344-3-christian.loehle@arm.com

include/uapi/linux/sched/types.h

@@ -58,9 +58,9 @@
  *
  * This is reflected by the following fields of the sched_attr structure:
  *
- *  @sched_deadline	representative of the task's deadline
- *  @sched_runtime	representative of the task's runtime
- *  @sched_period	representative of the task's period
+ *  @sched_deadline	representative of the task's deadline in nanoseconds
+ *  @sched_runtime	representative of the task's runtime in nanoseconds
+ *  @sched_period	representative of the task's period in nanoseconds
  *
  * Given this task model, there are a multiplicity of scheduling algorithms
  * and policies, that can be used to ensure all the tasks will make their