Fix distributed types support for CPUs

[kaushikb11]

What does this PR do?

Fixes distributed types support for CPUs(DistributedType.DP, DistributedType.DDP2).
Change it to ddp, if dp or ddp2 is passed for cpus.

Does your PR introduce any breaking changes? If yes, please list them.

Before submitting

• Was this discussed/approved via a GitHub issue? (not for typos and docs)
• Did you read the contributor guideline, Pull Request section?
• Did you make sure your PR does only one thing, instead of bundling different changes together?
• Did you make sure to update the documentation with your changes? (if necessary)
• Did you write any new necessary tests? (not for typos and docs)
• Did you verify new and existing tests pass locally with your changes?
• Did you list all the breaking changes introduced by this pull request?
• Did you update the CHANGELOG? (not for typos, docs, test updates, or internal minor changes/refactorings)

PR review

Anyone in the community is welcome to review the PR.
Before you start reviewing make sure you have read Review guidelines. In short, see the following bullet-list:

• Is this pull request ready for review? (if not, please submit in draft mode)
• Check that all items from Before submitting are resolved
• Make sure the title is self-explanatory and the description concisely explains the PR
• Add labels and milestones (and optionally projects) to the PR so it can be classified

Did you have fun?

Make sure you had fun coding 🙃

[codecov]

Codecov Report

Merging #8667 (a5c0d61) into master (85bba06) will decrease coverage by 4%.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master   #8667    +/-   ##
=======================================
- Coverage      93%     88%    -4%     
=======================================
  Files         168     168            
  Lines       13984   13985     +1     
=======================================
- Hits        12948   12355   -593     
- Misses       1036    1630   +594     

[awaelchli]

@kaushikb11 there are failing tests, likely due to the change to the num_gpus -> has_gpu change