selftests/mm/uffd: refactor non-composite global vars into struct

selftests/mm/uffd: refactor non-composite global vars into struct

Refactor macros and non-composite global variable definitions into a
struct that is defined at the start of a test and is passed around instead
of relying on global vars.

Link: https://lkml.kernel.org/r/20250829155600.2000-1-ujwal.kundur@gmail.com
Signed-off-by: Ujwal Kundur <ujwal.kundur@gmail.com>
Acked-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Brendan Jackman <jackmanb@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>