net: marvell: prestera: fix memory leak in prestera_rxtx_switch_init()

When prestera_sdma_switch_init() failed, the memory pointed to by
sw->rxtx isn't released. Fix it. Only be compiled, not be tested.

Fixes: 501ef306 ("net: marvell: prestera: Add driver for Prestera family ASIC devices")
Signed-off-by: NZhengchao Shao <shaozhengchao@huawei.com>
Reviewed-by: NVadym Kochan <vadym.kochan@plvision.eu>
Link: https://lore.kernel.org/r/20221108025607.338450-1-shaozhengchao@huawei.comSigned-off-by: NJakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/marvell/prestera/prestera_rxtx.c

@@ -776,6 +776,7 @@ static netdev_tx_t prestera_sdma_xmit(struct prestera_sdma *sdma,
 int prestera_rxtx_switch_init(struct prestera_switch *sw)
 {
 	struct prestera_rxtx *rxtx;
+	int err;
 
 	rxtx = kzalloc(sizeof(*rxtx), GFP_KERNEL);
 	if (!rxtx)
@@ -783,7 +784,11 @@ int prestera_rxtx_switch_init(struct prestera_switch *sw)
 
 	sw->rxtx = rxtx;
 
-	return prestera_sdma_switch_init(sw);
+	err = prestera_sdma_switch_init(sw);
+	if (err)
+		kfree(rxtx);
+
+	return err;
 }
 
 void prestera_rxtx_switch_fini(struct prestera_switch *sw)