gitlab-ci.yml: Use correct CI variable name

The unfortunate typo caused the build-docs job to always build main,
not what was being tested!

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@huawei.com>

.gitlab-ci.yml

@@ -31,7 +31,7 @@ reuse:
 # incoming changes that match the repository holding this CI pipeline.
 .workspace:
   variables:
-    OHOS_GIT_REPO_PATH: docs
+    OHOS_CI_GIT_REPO_PATH: docs
 
 # Disable all the bitbake jobs, since we are not building any code here.
 .bitbake-workspace: