edac: Move grain/dtype/edac_type calculus to be out of channel loop

The 3e7bddc changeset (edac: move dimm properties to struct memset_info)
moved the calculus inside a loop. However, at those stuff are common to
all channels, on several drivers, it is better to put the calculus
outside the loop, to optimize the code.

Reported-by: Aristeu Rozanski Filho <arozansk@redhat.com>
Reviewed-by: Aristeu Rozanski <arozansk@redhat.com>
Cc: Mark Gross <mark.gross@intel.com>
Cc: Doug Thompson <norsk5@yahoo.com>
Cc: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Michal Marek <mmarek@suse.cz>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>