This commit replaces the "used" field of irq_desc with a bitmap to maintain
the irq use status to save memory and LOC, and improve the efficiency as well.
Signed-off-by: Yan, Like <like.yan@intel.com>
Reviewed-by: Li, Fei1 <fei1.li@intel.com>
Acked-by: Anthony Xu <anthony.xu@intel.com>