genirq: Add IRQ_AFFINITY_MANAGED flag

Add IRQ_AFFINITY_MANAGED flag and related kernel APIs so that
kernel driver can modify an irq's status in such a way that
user space affinity change will be ignored. Kernel space's
affinity setting will not be changed.

Change-Id: Ib2d5ea651263bff4317562af69079ad950c9e71e
Signed-off-by: Runmin Wang <runminw@codeaurora.org>