net: ngbe: fix memory leak in ngbe_probe() error path

In the Linux kernel, the following vulnerability has been resolved:

net: ngbe: fix memory leak in ngbe_probe() error path

When ngbe_sw_init() is called, memory is allocated for wx->rss_key

in wx_init_rss_key(). However, in ngbe_probe() function, the subsequent

error paths after ngbe_sw_init() don't free the rss_key. Fix that by

freeing it in error path along with wx->mac_table.

Also change the label to which execution jumps when ngbe_sw_init()

fails, because otherwise, it could lead to a double free for rss_key,

when the mac_table allocation fails in wx_sw_init().