Revert "sh_eth: remove open coded netif_running()"

Revert "sh_eth: remove open coded netif_running()"

This reverts commit ce1fdb065695f49ef6f126d35c1abbfe645d62d5. It turned
out this actually introduces a race condition. netif_running() is not a
suitable check for get_stats.

Reported-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/20230327152112.15635-1-wsa+renesas@sang-engineering.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>