Enables multi-arch image builds for s390x platform

[ashokpariya0]

This allows building and publishing SR-IOV CNI images for s390x (IBM Z / LinuxONE) architecture.

Fixes: #379

[SchSeba]

LGTM

[coveralls]

Pull Request Test Coverage Report for Build 18836109589

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 62.889%

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Totals
Change from base Build 18815390783:	0.0%
Covered Lines:	971
Relevant Lines:	1544

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💛 - Coveralls

[ashokpariya0]

@SchSeba It seems job: Mellanox CI https://github.com/Mellanox/kubernetes-ci is stuck, do we need to do anything for this?

All other tests have passed.

[SchSeba]

Hi @ashokpariya0 yep we need another maintainer to approve before we can merge it.
@e0ne please take a look when you have time

[ashokpariya0]

Thanks @SchSeba ,
Could you please check this @e0ne @adrianchiris @zeeke