MAINTAINERS: ena: remove Zorik Machulsky from reviewers

MAINTAINERS: ena: remove Zorik Machulsky from reviewers

While ENA has 3 reviewers and 2 maintainers, we mostly see review
tags and comments from the maintainers. While we very much appreciate
Zorik's invovment in the community let's trim the reviewer list
down to folks we've seen tags from.

Subsystem AMAZON ETHERNET DRIVERS
  Changes 13 / 269 (4%)
  Last activity: 2020-11-24
  Netanel Belgazal <netanel@amazon.com>:
    Author df3a957ebd50 2019-12-10 00:00:00 43
    Tags 08221af8f936 2020-07-21 00:00:00 47
  Arthur Kiyanovski <akiyano@amazon.com>:
    Author 08221af8f936 2020-07-21 00:00:00 79
    Tags eb5292fcaf9e 2020-11-24 00:00:00 104
  Guy Tzalik <gtzalik@amazon.com>:
    Tags 8abd157b20fb 2020-09-10 00:00:00 3
  Saeed Bishara <saeedb@amazon.com>:
    Tags 319656fd882e 2020-02-11 00:00:00 2
  Zorik Machulsky <zorik@amazon.com>:
  Top reviewers:
    [4]: sameehj@amazon.com
    [3]: snelson@pensando.io
    [3]: shayagr@amazon.com
  INACTIVE MAINTAINER Zorik Machulsky <zorik@amazon.com>

Signed-off-by: Jakub Kicinski <kuba@kernel.org>