mailmap: update entry for David Heidelberg

Link my old gmail address to my active email.

Link: https://lkml.kernel.org/r/20240804054704.859503-1-david@ixit.cz


Signed-off-by: David Heidelberg <david@ixit.cz>
Cc: David S. Miller <davem@davemloft.net>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>