r8169: remove non-napi code

It will almost unavoidably cause some breakage but it
is long overdue.

The driver identification string has been updated, a
lost tabulation and some unused code have been removed.
Otherwise the code paths should stay the same.

Signed-off-by: Francois Romieu <romieu@fr.zoreil.com>
Cc: Edward Hsu <edward_hsu@realtek.com.tw>