selftests/mm: allocate 6 hugepages in va_high_addr_switch.sh

selftests/mm: allocate 6 hugepages in va_high_addr_switch.sh

The va_high_addr_switch test requires 6 hugepages, not 5. If running the
test directly by: ./va_high_addr_switch.sh, the test will hit a mmap 'FAIL'
caused by not enough hugepages:

  mmap(addr_switch_hint - hugepagesize, 2*hugepagesize, MAP_HUGETLB): 0x7f330f800000 - OK
  mmap(addr_switch_hint , 2*hugepagesize, MAP_FIXED | MAP_HUGETLB): 0xffffffffffffffff - FAILED

The failure can't be hit if run the tests by running 'run_vmtests.sh -t
hugevm' because the nr_hugepages is set to 128 at the beginning of
run_vmtests.sh and va_high_addr_switch.sh skip the setup of nr_hugepages
because already enough.

Link: https://lkml.kernel.org/r/20251221040025.3159990-2-chuhu@redhat.com
Fixes: d9d957bd7b61 ("selftests/mm: alloc hugepages in va_high_addr_switch test")
Signed-off-by: Chunyu Hu <chuhu@redhat.com>
Reviewed-by: Luiz Capitulino <luizcap@redhat.com>
Cc: "David Hildenbrand (Red Hat)" <david@kernel.org>
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>