staging: octeon-ethernet: delete references to CONFIG_CAVIUM_RESERVE32

Delete references to CONFIG_CAVIUM_RESERVE32. Kernel does not have such
option and the driver does not use it for anything.

Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>