mailmap: add entry for <mstarovoitov@marvell.com>

Map the address to my private mail, because my Marvell account has been suspended.

Signed-off-by: Mark Starovoytov <mstarovo@pm.me>
Link: https://lore.kernel.org/r/20200928183948.589-1-mstarovo@pm.me


Signed-off-by: Jonathan Corbet <corbet@lwn.net>