genirq: Don't allow user space to set IRQ affinity to isolated CPUs

The PM_QOS_CPU_DMA_LATENCY QOS request attached to an IRQ is ignored
if the IRQ is affined to an isolated CPU. As isolated CPUs enter
deep sleep state, it is better not to affine IRQs to those CPUs.

Change-Id: Ieab4a04eca222b91159208b21bc9e14390ecd62e
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>