cxgb4: fix missing break in switch and indent return statements

The break statement for the Macronix case is missing and will
fall through to the Winbond case and re-assign the size setting.
Fix this by adding the missing break statement.  Also correctly
indent the return statements.

Detected by CoverityScan, CID#1458020 ("Missing break in switch")

Fixes: 96ac18f1 ("cxgb4: Add support for new flash parts")
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/chelsio/cxgb4/t4_hw.c

@@ -8425,6 +8425,7 @@ static int t4_get_flash_params(struct adapter *adap)
 				flashid, density);
 			return -EINVAL;
 		}
+		break;
 	}
 	case 0xef: { /* Winbond */
 		/* This Density -> Size decoding table is taken from Winbond