free_irq() should not be executed from softirq context.

Found by the lock validator.  The fix is to push fd_free_irq() into
keventd.  The code validates fine with this patch applied.

(akpm: this is revolting, but so is floppy.c)

[akpm@osdl.org: added flush_scheduled_work()]
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>