sched/headers, x86/apic: Remove the <linux/pm.h> header inclusion from <asm/apic.h>

We want to simplify <linux/sched.h>'s header dependencies, but one
roadblock to that is <asm/apic.h>'s inclusion of pm.h,
which brings in other, problematic headers.

Remove it, as it appears to be entirely spurious, apic.h does not
actually make use of any PM facilities.

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>