selftests/move_mount_set_group remove unneeded conversion to bool

The coccinelle report
./tools/testing/selftests/move_mount_set_group/move_mount_set_group_test.c:225:18-23:
WARNING: conversion to bool not needed here
Relational and logical operators evaluate to bool,
explicit conversion is overly verbose and unneeded.

Reported-by: Zeal Robot <[e-mail]>
Signed-off-by: Yang Guang <[e-mail]>
Signed-off-by: Shuah Khan <[e-mail]>

tools/testing/selftests/move_mount_set_group/move_mount_set_group_test.c

···
 #define SET_GROUP_FROM	"/tmp/move_mount_set_group_supported_from"
 #define SET_GROUP_TO	"/tmp/move_mount_set_group_supported_to"
 
-static int move_mount_set_group_supported(void)
+static bool move_mount_set_group_supported(void)
 {
 	int ret;
 
···
 		      AT_FDCWD, SET_GROUP_TO, MOVE_MOUNT_SET_GROUP);
 	umount2("/tmp", MNT_DETACH);
 
-	return ret < 0 ? false : true;
+	return ret >= 0;
 }
 
 FIXTURE(move_mount_set_group) {
···
 
 FIXTURE_SETUP(move_mount_set_group)
 {
-	int ret;
+	bool ret;
 
 	ASSERT_EQ(prepare_unpriv_mountns(), 0);
 
···
 
 FIXTURE_TEARDOWN(move_mount_set_group)
 {
-	int ret;
+	bool ret;
 
 	ret = move_mount_set_group_supported();
 	ASSERT_GE(ret, 0);
···
 		.shared = false,
 	};
 	pid_t pid;
-	int ret;
+	bool ret;
 
 	ret = move_mount_set_group_supported();
 	ASSERT_GE(ret, 0);