syscalls/statx06: use a fine-grained timestamp for the second time fetch

I have a patchset in progress to change the kernel to sometimes use
fine-grained timestamps for the mtime/ctime. With this, the statx06 test
sometimes fails.

Change the test to grab a fine-grained timestamp for the "after" value,
which fixes the issue.

Link: https://lore.kernel.org/ltp/[email protected]/
Reviewed-by: Cyril Hrubis <[email protected]>
Reviewed-by: Petr Vorel <[email protected]>
Reviewed-by: Yang Xu <[email protected]>
[ pvorel: Although patchset [1] has not been merged, we agreed that
the change is backward compatible anyway. ]
Signed-off-by: Jeff Layton <[email protected]>

[1] https://lore.kernel.org/lkml/[email protected]/

Author: jtlayton

testcases/kernel/syscalls/statx/statx06.c

@@ -109,7 +109,7 @@ static void test_statx(unsigned int test_nr)
 	clock_wait_tick();
 	tc->operation();
 	clock_wait_tick();
-	SAFE_CLOCK_GETTIME(CLOCK_REALTIME_COARSE, &after_time);
+	SAFE_CLOCK_GETTIME(CLOCK_REALTIME, &after_time);
 
 	TEST(statx(AT_FDCWD, TEST_FILE, 0, STATX_BASIC_STATS | STATX_BTIME, &buff));
 	if (TST_RET != 0) {