mailmap: Add entry for Damian Hobson-Garcia.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

.mailmap

@@ -32,6 +32,7 @@ Brian Avery <b.avery@hp.com>
 Brian King <brking@us.ibm.com>
 Christoph Hellwig <hch@lst.de>
 Corey Minyard <minyard@acm.org>
+Damian Hobson-Garcia <dhobsong@igel.co.jp>
 David Brownell <david-b@pacbell.net>
 David Woodhouse <dwmw2@shinybook.infradead.org>
 Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>