cpuset_memory_testset.sh: Fix syntax error when hugepages not supported

The initial hugepage size calculation can result in multiplication
of empty string on machines which don't support hugepages. Make
sure that empty string is converted to zero.

Signed-off-by: Martin Doucha <mdoucha@suse.cz>
Reviewed-by: Li Wang <liwang@redhat.com>

testcases/kernel/controllers/cpuset/cpuset_memory_test/cpuset_memory_testset.sh

@@ -41,7 +41,7 @@ mems_all="$(seq -s, 0 $((nr_mems-1)))"
 cpu_of_node0=0
 
 HUGEPAGESIZE=$(awk '/Hugepagesize/{ print $2 }' /proc/meminfo)
-HUGEPAGESIZE=$(($HUGEPAGESIZE * 1024))
+HUGEPAGESIZE=$((${HUGEPAGESIZE:-0} * 1024))
 
 MEMORY_RESULT="$CPUSET_TMP/memory_result"