mwifiex: do not overwrite error code from lower layer driver

Instead of converting it to a bogus error code -1, we should
return the original error code from lower layer driver. This
error code will be printed so it may give user some clues on
what has happened.

Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/mwifiex/usb.c b/drivers/net/wireless/mwifiex/usb.c
index 5d4a10a..f90fe21 100644
--- a/drivers/net/wireless/mwifiex/usb.c
+++ b/drivers/net/wireless/mwifiex/usb.c
@@ -672,7 +672,7 @@
 			   *len, &actual_length, timeout);
 	if (ret) {
 		dev_err(adapter->dev, "usb_bulk_msg for tx failed: %d\n", ret);
-		ret = -1;
+		return ret;
 	}
 
 	*len = actual_length;
@@ -691,7 +691,7 @@
 			   *len, &actual_length, timeout);
 	if (ret) {
 		dev_err(adapter->dev, "usb_bulk_msg for rx failed: %d\n", ret);
-		ret = -1;
+		return ret;
 	}
 
 	*len = actual_length;