selftests/mm: fix check for running THP tests

When testing if we should try to compact memory or drop caches before we
run the THP or HugeTLB tests we use | as an or operator.  This doesn't
work since run_vmtests.sh is written in shell where this is used to pipe
the output of the first argument into the second.  Instead use the shell's
-o operator.

Link: https://lkml.kernel.org/r/20250212-kselftest-mm-no-hugepages-v1-1-44702f538522@kernel.org


Fixes: b433ffa8 ("selftests: mm: perform some system cleanup before using hugepages")
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Nico Pache <npache@redhat.com>
Cc: Mariano Pache <npache@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>