selftests/bpf: Fix htab_update/reenter_update selftest failure

Since commit 31158ad ("rqspinlock: Add deadlock detection and recovery")
the updated path on re-entrancy now reports deadlock via
-EDEADLK instead of the previous -EBUSY.

The selftest is updated to align with expected errno
with the kernel’s current behavior.

Signed-off-by: Saket Kumar Bhaskar <[email protected]>

Author: Saket Kumar Bhaskar

tools/testing/selftests/bpf/prog_tests/htab_update.c

@@ -40,7 +40,7 @@ static void test_reenter_update(void)
 	if (!ASSERT_OK(err, "add element"))
 		goto out;
 
-	ASSERT_EQ(skel->bss->update_err, -EBUSY, "no reentrancy");
+	ASSERT_EQ(skel->bss->update_err, -EDEADLK, "no reentrancy");
 out:
 	htab_update__destroy(skel);
 }