interrupt_controller: ioapic_intr: revert CPU target change

Commit 5a9a33b0 changes interrupt
destination in an attempt to broadcast interrupts. However, this
change causes interrupts to stop working on the UP Squared board
in non-SMP configuration. According to QEMU source code,
physical destination address 0xFF000000 is a special case where
it broadcasts the interrupts. However, none of the IOAPIC
documentation (that I can find) describes this behavior. So,
revert that commit.

Signed-off-by: Daniel Leung <daniel.leung@intel.com>