x86/hyperv/vtl: Add noop for realmode pointers

Assign the realmode pointers to noop, instead of NULL to fix kernel panic.

Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/1682331016-22561-1-git-send-email-ssengar@linux.microsoft.com


Signed-off-by: Wei Liu <wei.liu@kernel.org>