sched/headers: ARM needs asm/paravirt_api_clock.h too

Add <asm/paravirt_api_clock.h> for arch/arm/, mapped to <asm/paravirt.h>,
to simplify #ifdeffery in generic code.

Fixes this build error introduced by the scheduler tree:

  In file included from ../kernel/sched/core.c:81:
  ../kernel/sched/sched.h:87:11: fatal error: asm/paravirt_api_clock.h: No such file or directory
     87 | # include <asm/paravirt_api_clock.h>

Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Fixes: 4ff8f2ca

 ("sched/headers: Reorganize, clean up and optimize kernel/sched/sched.h dependencies")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20220316204146.14000-1-rdunlap@infradead.org