tests: remove unavailable requirements for s390x

lld and libomp are not shipped in s390x, hence causing provisioning
prepare step to fail as they are required in llvm-integration-testsuite.
The test should still run fine without those packages.

tests/integration-test-suite/main.fmf

@@ -24,6 +24,14 @@ adjust:
       - python3-lit
     when: "collection is not defined"
 
+  # lld and libomp are not supported in s390x, remove them
+  - require-:
+      - lld
+      - libomp-devel
+    when: >-
+      collection is not defined
+      and arch == s390x
+
   # Requirements for SCL-ized LLVM
   - require+:
       - llvm-toolset-13.0-cmake
@@ -39,6 +47,14 @@ adjust:
       - llvm-toolset-13.0-python3-lit
     when: "collection == llvm-toolset-13.0"
 
+  # lld and libomp are not supported in s390x, remove them
+  - require-:
+      - llvm-toolset-13.0-lld
+      - llvm-toolset-13.0-libomp-devel
+    when: >-
+      collection == llvm-toolset-13.0
+      and arch == s390x
+
   # libcxx shall be required in Fedora, it's not shipped with RHEL.
   - require+:
       - libcxx-devel