staging: octeon: remove unused variable

A cleanup patch left one local variable without a reference:

drivers/staging/octeon/ethernet-rx.c:339:28: warning: unused variable 'priv' [-Wunused-variable]

This removes the declaration too.

Fixes: 66812da3

 ("staging: octeon: Use net_device_stats from struct net_device")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>