Move the arm call to intr_pic_init_secondary earlier in the secondary CPU
initialisation. This ensures it will complete before signalling to the boot
CPU it has booted. This fixes a race with the GIC where the arm_gic_map may
not be populated before it is used to bind interrupts leading to some
interrupts becoming bound to no CPUs.

Approved by: re (kib)
Sponsored by: ABT Systems Ltd