Allow to modify the per-socket irq_mask via sysfs.  Note that you can only
clear bits from the mask, but not re-add bits.
Signed-off-by: Dominik Brodowski <linux@brodo.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>