intel/e1000e:fix repeated words in comments

Delete the redundant word 'frames'.

Signed-off-by: Jilin Yuan <[e-mail]>
Signed-off-by: Tony Nguyen <[e-mail]>

drivers/net/ethernet/intel/e1000e/mac.c

···
 	 *      1:  Rx flow control is enabled (we can receive pause
 	 *          frames but not send pause frames).
 	 *      2:  Tx flow control is enabled (we can send pause frames
-	 *          frames but we do not receive pause frames).
+	 *          but we do not receive pause frames).
 	 *      3:  Both Rx and Tx flow control (symmetric) is enabled.
 	 *  other:  No other values should be possible at this point.
 	 */