[CORE] Increase max IPIs per host CPU

Limiting max IPIs to be host CPU count seems to be an underestimate
of required number of max IPIs per host CPU. Due to this we quite
frequently run out of space in IPI fifo.

For now, this patch set max IPIs per host CPU to max VCPU count.

Signed-off-by: Anup Patel <anup@brainfault.org>