edac: Allow panic on correctable errors (CE)

Add an EDAC device flag and associated sysfs entries to
allow an EDAC driver to be configured to panic the kernel
if a correctable error is detected. Though correctable
errors (by definition) have no adverse system effects,
a panic may still be useful, since a correctable error may
be indicative of a marginal system state.

Change-Id: I98921469254aa7b999979c1c7d9186286f982a0c
Signed-off-by: Stepan Moskovchenko <stepanm@codeaurora.org>