Remove merged MPICH patch

Reviewed-by: Aleix Roca Nonell <aleix.rocanonell@bsc.es>

pkgs/mpich-fix-hwtopo.patch

@@ -1,36 +0,0 @@
-diff --git a/src/util/mpir_hwtopo.c b/src/util/mpir_hwtopo.c
-index 33e88bc..ee3641c 100644
---- a/src/util/mpir_hwtopo.c
-+++ b/src/util/mpir_hwtopo.c
-@@ -200,18 +200,6 @@ int MPII_hwtopo_init(void)
- #ifdef HAVE_HWLOC
-     bindset = hwloc_bitmap_alloc();
-     hwloc_topology_init(&hwloc_topology);
--    char *xmlfile = MPIR_pmi_get_jobattr("PMI_hwloc_xmlfile");
--    if (xmlfile != NULL) {
--        int rc;
--        rc = hwloc_topology_set_xml(hwloc_topology, xmlfile);
--        if (rc == 0) {
--            /* To have hwloc still actually call OS-specific hooks, the
--             * HWLOC_TOPOLOGY_FLAG_IS_THISSYSTEM has to be set to assert that the loaded
--             * file is really the underlying system. */
--            hwloc_topology_set_flags(hwloc_topology, HWLOC_TOPOLOGY_FLAG_IS_THISSYSTEM);
--        }
--        MPL_free(xmlfile);
--    }
-
-     hwloc_topology_set_io_types_filter(hwloc_topology, HWLOC_TYPE_FILTER_KEEP_ALL);
-     if (!hwloc_topology_load(hwloc_topology)) 
-
---- a/src/mpi/init/local_proc_attrs.c
-+++ b/src/mpi/init/local_proc_attrs.c
-@@ -79,10 +79,6 @@ int MPII_init_local_proc_attrs(int *p_thread_required)
-     /* Set the number of tag bits. The device may override this value. */
-     MPIR_Process.tag_bits = MPIR_TAG_BITS_DEFAULT;
-
--    char *requested_kinds = MPIR_pmi_get_jobattr("PMI_mpi_memory_alloc_kinds");
--    MPIR_get_supported_memory_kinds(requested_kinds, &MPIR_Process.memory_alloc_kinds);
--    MPL_free(requested_kinds);
--
-     return mpi_errno;
- }

pkgs/overlay.nix

@@ -11,10 +11,6 @@ final: prev:
       paths = [ pmix.dev pmix.out ];
     };
   in prev.mpich.overrideAttrs (old: {
-    patches = (old.patches or []) ++ [
-      # See https://github.com/pmodels/mpich/issues/6946
-      ./mpich-fix-hwtopo.patch
-    ];
     buildInput = old.buildInputs ++ [
       libfabric
       pmixAll