edac: ppc mpc85xx fix mc err detect

Error found by Jeff Haran.

The error detect register is 0s when no errors are detected.  The check
code is incorrect, so reverse check sense.
Reported-by: NJeff Haran <jharan@Brocade.COM>
Signed-off-by: NDave Jiang <djiang@mvista.com>
Signed-off-by: NDoug Thompson <dougthompson@xmission.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: NKumar Gala <galak@kernel.crashing.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/edac/mpc85xx_edac.c

@@ -674,7 +674,7 @@ static void mpc85xx_mc_check(struct mem_ctl_info *mci)
 	int row_index;
 
 	err_detect = in_be32(pdata->mc_vbase + MPC85XX_MC_ERR_DETECT);
-	if (err_detect)
+	if (!err_detect)
 		return;
 
 	mpc85xx_mc_printk(mci, KERN_ERR, "Err Detect Register: %#8.8x\n",