atusb: don't change csma settings while set channel

This patch fixes the behaviour to not overwrite csma settings when
set channel afterwards.

Cc: Stefan Schmidt <stefan@osg.samsung.com>
Acked-by: NStefan Schmidt <stefan@osg.samsung.com>
Signed-off-by: NAlexander Aring <aar@pengutronix.de>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

drivers/net/ieee802154/atusb.c

@@ -366,11 +366,7 @@ static int atusb_channel(struct ieee802154_hw *hw, u8 page, u8 channel)
 	struct atusb *atusb = hw->priv;
 	int ret;
 
-	/* This implicitly sets the CCA (Clear Channel Assessment) mode to 0,
-	 * "Mode 3a, Carrier sense OR energy above threshold".
-	 * We should probably make this configurable. @@@
-	 */
-	ret = atusb_write_reg(atusb, RG_PHY_CC_CCA, channel);
+	ret = atusb_write_subreg(atusb, SR_CHANNEL, channel);
 	if (ret < 0)
 		return ret;
 	msleep(1);	/* @@@ ugly synchronization */