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: Zhengchao Shao <shaozhengchao@huawei.com>
Reviewed-by: Vadym Kochan <vadym.kochan@plvision.eu>
Link: https://lore.kernel.org/r/20221108025607.338450-1-shaozhengchao@huawei.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>