staging: octeon-usb: delete redundant field from octeon_temp_buffer

Since we are not moving/realigning the original pointer returned
by kmalloc, we don't need to store the value in a separate field.

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