x86/ioapic/32: Decrapify phys_id_present_map operation

The operation to set the IOAPIC ID in phys_id_present_map is as convoluted
as it can be.

  1) Allocate a bitmap of 32byte size on the stack
  2) Zero the bitmap and set the IOAPIC ID bit
  3) Or the temporary bitmap over phys_id_present_map

The same functionality can be achieved by setting the IOAPIC ID bit
directly in the phys_id_present_map.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Tested-by: Juergen Gross <jgross@suse.com> # Xen PV (dom0 and unpriv. guest)