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 bbc39bbe1f3b 2019-12-10 00:00:00 43
    Tags f362261cb4bc 2020-07-21 00:00:00 47
  Arthur Kiyanovski <akiyano@amazon.com>:
    Author f362261cb4bc 2020-07-21 00:00:00 79
    Tags 111ddc04cbeb 2020-11-24 00:00:00 104
  Guy Tzalik <gtzalik@amazon.com>:
    Tags 2a51d88248a5 2020-09-10 00:00:00 3
  Saeed Bishara <saeedb@amazon.com>:
    Tags 3d0c6428b86a 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>