selftests/mm: parse VMA range in one go

Use sscanf() to directly parse the VMA range. No functional change is intended.

Link: https://lkml.kernel.org/r/20240322120551.818764-1-dev.jain@arm.com


Signed-off-by: Dev Jain <dev.jain@arm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>