selftests/eventfd: correct test name and improve messages

- Rename test from eventfd_chek_flag_cloexec_and_nonblock to
eventfd_check_flag_cloexec_and_nonblock.

- Make the RDWR‐flag comment declarative:
“The kernel automatically adds the O_RDWR flag.”
- Update semaphore‐flag failure message to:
“eventfd semaphore flag check failed: …”

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Ryan Chung <[e-mail]>
Reviewed-by: Wen Yang <[e-mail]>
Cc: Shuah Khan <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

tools/testing/selftests/filesystems/eventfd/eventfd_test.c

···
 	ASSERT_GE(fd, 0);
 
 	flags = fcntl(fd, F_GETFL);
-	// since the kernel automatically added O_RDWR.
+	// The kernel automatically adds the O_RDWR flag.
 	EXPECT_EQ(flags, O_RDWR);
 
 	close(fd);
···
 	close(fd);
 }
 
-TEST(eventfd_chek_flag_cloexec_and_nonblock)
+TEST(eventfd_check_flag_cloexec_and_nonblock)
 {
 	int fd, flags;
 
···
 	// The semaphore could only be obtained from fdinfo.
 	ret = verify_fdinfo(fd, &err, "eventfd-semaphore: ", 19, "1\n");
 	if (ret != 0)
-		ksft_print_msg("eventfd-semaphore check failed, msg: %s\n",
-				err.msg);
+		ksft_print_msg("eventfd semaphore flag check failed: %s\n", err.msg);
 	EXPECT_EQ(ret, 0);
 
 	close(fd);