memblock tests: remove completed TODO item

Remove completed item from TODO list.
Reviewed-by: NDavid Hildenbrand <david@redhat.com>
Signed-off-by: NRebecca Mckeever <remckee0@gmail.com>
Signed-off-by: NMike Rapoport <rppt@linux.ibm.com>
Link: https://lore.kernel.org/r/f2263abe45613b28f1583fbf04a4bffcf735bcf6.1667802195.git.remckee0@gmail.com

tools/testing/memblock/TODO

 TODO
 =====
 
-1. Add test cases using this functions (implement them for both directions):
-   + memblock_alloc_raw()
-   + memblock_alloc_exact_nid_raw()
-   + memblock_alloc_try_nid_raw()
-
-2. Add tests for memblock_alloc_node() to check if the correct NUMA node is set
+1. Add tests for memblock_alloc_node() to check if the correct NUMA node is set
    for the new region