edac: core fix workq timer

When updating the edac_mc_poll_msec module parameter from the sysfs
/sys/module/edac_core/parameters/edac_mc_poll_msec file, we don't update
the workq timers.  So that, if we move from a big poll time to a small
one, the small one won't take effect until the big one has timed out.

Here we provide a new module parameter set method to call out to the
update routine.  This brings the /sys/module/edac_core/parameters
functionality up to that provided by the /sys/drivers/system/edac/mc sysfs
module parameter files so that we can remove them or at least link to the
/sys/module files...

Signed-off-by: Arthur Jones <ajones@riverbed.com>
Signed-off-by: Doug Thompson <dougthompson@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>