selftests/mm: deduplicate default page size test results in thuge-gen

The thuge-gen test program runs mmap() and shmget() tests for both every
available page size and the default page size, resulting in two tests for
the default size.  These tests are distinct since the flags in the default
case do not specify an explicit size, add the flags to the test name that
is logged to deduplicate.

Link: https://lkml.kernel.org/r/20250515-selfests-mm-thuge-gen-dup-v1-1-057d2836553f@kernel.org


Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Dev Jain <dev.jain@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>