Make devsetup/cifwm_prepare not fail when rerun

Currently if one tries to rerun cifwm_prepare it fails
on git cloning attempt since the directory is already in place.

Example of failure:
> + make cifmw_prepare
> git clone https://github.com/openstack-k8s-operators/ci-framework ci-framework
> fatal: destination path 'ci-framework' already exists and is not an empty directory.
> make: *** [Makefile:180: cifmw_prepare] Error 128

As that is not expected from make target, make it so that
this target depends on the directory existing target,
which itself calls the git clone for its creation.

devsetup/Makefile

@@ -219,7 +219,10 @@ standalone_revert: ## Revert standalone snapshot
 	virsh --connect=qemu:///system snapshot-revert --domain edpm-compute-${EDPM_COMPUTE_SUFFIX} --snapshotname clean
 
 .PHONY: cifmw_prepare
-cifmw_prepare: ## Clone the ci-framework repository in the ci-framework directory. That location is ignored from git.
+cifmw_prepare: ./ci-framework ## Clone or pull the ci-framework repository in the ci-framework directory. That location is ignored from git.
+	cd ci-framework && [[ -n "$$(git status --porcelain)" ]] || git pull --rebase
+
+./ci-framework: ## Actual git-cloning if the cifmw directory does not exist yet (make calls this only if target path is not there)
 	git clone https://github.com/openstack-k8s-operators/ci-framework ci-framework
 
 .PHONY: cifmw_cleanup