sh_eth: kill useless initializers in sh_eth_{suspend|resume}()

sh_eth_{suspend|resume}() initialize their local variable 'ret' to 0 but
this value is never really used, thus we can kill those intializers...

Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Link: https://lore.kernel.org/r/f09d7c64-4a2b-6973-09a4-10d759ed0df4@omp.ru
Signed-off-by: Jakub Kicinski <kuba@kernel.org>