EDAC, sb_edac: Simplify switch statement

clang static analyzer reports this problem

sb_edac.c:959:2: warning: Undefined or garbage value
  returned to caller
        return type;
        ^~~~~~~~~~~

This is a false positive.

However by initializing the type to DEV_UNKNOWN the 3 case can be
removed from the switch, saving a comparison and jump.
Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Link: https://lore.kernel.org/r/20200907153225.7294-1-trix@redhat.com

drivers/edac/sb_edac.c

@@ -939,12 +939,9 @@ static enum dev_type sbridge_get_width(struct sbridge_pvt *pvt, u32 mtr)
 
 static enum dev_type __ibridge_get_width(u32 mtr)
 {
-	enum dev_type type;
+	enum dev_type type = DEV_UNKNOWN;
 
 	switch (mtr) {
-	case 3:
-		type = DEV_UNKNOWN;
-		break;
 	case 2:
 		type = DEV_X16;
 		break;