selftests/mm: fix awk usage in charge_reserved_hugetlb.sh and hugetlb_reparenting_test.sh that may cause error

According to the awk manual, the -e option does not need to be specified
in front of 'program' (unless you need to mix program-file).

The redundant -e option can cause error when users use awk tools other
than gawk (for example, mawk does not support the -e option).

Error Example:
awk: not an option: -e

Link: https://lkml.kernel.org/r/VI1P193MB075228810591AF2FDD7D42C599C3A@VI1P193MB0752.EURP193.PROD.OUTLOOK.COM
Signed-off-by: Juntong Deng <juntong.deng@outlook.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: juntongdeng

tools/testing/selftests/mm/charge_reserved_hugetlb.sh

@@ -25,15 +25,15 @@ if [[ "$1" == "-cgroup-v2" ]]; then
 fi
 
 if [[ $cgroup2 ]]; then
-  cgroup_path=$(mount -t cgroup2 | head -1 | awk -e '{print $3}')
+  cgroup_path=$(mount -t cgroup2 | head -1 | awk '{print $3}')
   if [[ -z "$cgroup_path" ]]; then
     cgroup_path=/dev/cgroup/memory
     mount -t cgroup2 none $cgroup_path
     do_umount=1
   fi
   echo "+hugetlb" >$cgroup_path/cgroup.subtree_control
 else
-  cgroup_path=$(mount -t cgroup | grep ",hugetlb" | awk -e '{print $3}')
+  cgroup_path=$(mount -t cgroup | grep ",hugetlb" | awk '{print $3}')
   if [[ -z "$cgroup_path" ]]; then
     cgroup_path=/dev/cgroup/memory
     mount -t cgroup memory,hugetlb $cgroup_path

tools/testing/selftests/mm/hugetlb_reparenting_test.sh

@@ -20,15 +20,15 @@ fi
 
 
 if [[ $cgroup2 ]]; then
-  CGROUP_ROOT=$(mount -t cgroup2 | head -1 | awk -e '{print $3}')
+  CGROUP_ROOT=$(mount -t cgroup2 | head -1 | awk '{print $3}')
   if [[ -z "$CGROUP_ROOT" ]]; then
     CGROUP_ROOT=/dev/cgroup/memory
     mount -t cgroup2 none $CGROUP_ROOT
     do_umount=1
   fi
   echo "+hugetlb +memory" >$CGROUP_ROOT/cgroup.subtree_control
 else
-  CGROUP_ROOT=$(mount -t cgroup | grep ",hugetlb" | awk -e '{print $3}')
+  CGROUP_ROOT=$(mount -t cgroup | grep ",hugetlb" | awk '{print $3}')
   if [[ -z "$CGROUP_ROOT" ]]; then
     CGROUP_ROOT=/dev/cgroup/memory
     mount -t cgroup memory,hugetlb $CGROUP_ROOT