edac: Don't initialize csrow's first_page & friends when not needed

Almost all edac	drivers	initialize csrow_info->first_page,
csrow_info->last_page and csrow_info->page_mask. Those vars are
used inside the EDAC core, in order to calculate the csrow affected
by an error, by using the routine edac_mc_find_csrow_by_page().

However, very few drivers actually use it:
        e752x_edac.c
        e7xxx_edac.c
        i3000_edac.c
        i82443bxgx_edac.c
        i82860_edac.c
        i82875p_edac.c
        i82975x_edac.c
        r82600_edac.c

There also a few other drivers that have their own calculus
formula internally using those vars.

All the others are just wasting time by initializing those
data.

While initializing data without using them won't cause any troubles, as
those information is stored at the wrong place (at csrows structure), it
is better to remove what is unused, in order to simplify the next patch.

Reviewed-by: Aristeu Rozanski <arozansk@redhat.com>
Acked-by: Borislav Petkov <borislav.petkov@amd.com>
Acked-by: Chris Metcalf <cmetcalf@tilera.com>
Cc: Doug Thompson <norsk5@yahoo.com>
Cc: Hitoshi Mitake <h.mitake@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: "Niklas Söderlund" <niklas.soderlund@ericsson.com>
Cc: Josh Boyer <jwboyer@gmail.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/edac/i7300_edac.c

@@ -778,7 +778,7 @@ static int i7300_init_csrows(struct mem_ctl_info *mci)
 	int rc = -ENODEV;
 	int mtr;
 	int ch, branch, slot, channel;
-	u32 last_page = 0, nr_pages;
+	u32 nr_pages;
 	struct dimm_info *dimm;
 
 	pvt = mci->pvt_info;
@@ -828,9 +828,6 @@ static int i7300_init_csrows(struct mem_ctl_info *mci)
 
 				/* Update per_csrow memory count */
 				p_csrow->nr_pages += nr_pages;
-				p_csrow->first_page = last_page;
-				last_page += nr_pages;
-				p_csrow->last_page = last_page;
 
 				rc = 0;
 			}