sched: Take irq_sparse lock during the isolation

irq_migrate_all_off_this_cpu() is used to migrate IRQs and this
function checks for all active irq in the allocated_irqs mask.
irq_migrate_all_off_this_cpu() expects the caller to take irq_sparse
lock to avoid race conditions while accessing allocated_irqs
mask variable. Prevent a race between irq alloc/free and irq
migration by adding irq_sparse lock across CPU isolation.

Change-Id: I9edece1ecea45297c8f6529952d88b3133046467
Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>