LU-15182 git: Add .gitreview file

LU-15182 git: Add .gitreview file

Add .gitreview file, so that we can use "git review -s" to setup
remote push url and use "git review" to send patch for review.

Git review cmd is a very convenient tool to push, review for
Gerrit review system. See more details here:
https://docs.opendev.org/opendev/git-review/latest/usage.html

Test-Parameters: trivial
Change-Id: Ic8223bdfcb7a696328f921159a63d625359e45a6
Signed-off-by: Xinliang Liu <xinliang.liu@linaro.org>
Reviewed-on: https://review.whamcloud.com/44907
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Oleg Drokin <green@whamcloud.com>