mailmap: add Boris Brezillon's email

There are different versions of Boris' name and email in the log, and
one typo.  Add his emails in mailmap to have all of his contributions
under the same name/email tuple.

Link: http://lkml.kernel.org/r/20160609130323.27706-2-antoine.tenart@free-electrons.com
Signed-off-by: Antoine Tenart <antoine.tenart@free-electrons.com>
Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

.mailmap

@@ -31,6 +31,9 @@ Axel Lin <axel.lin@gmail.com>
 Ben Gardner <bgardner@wabtec.com>
 Ben M Cahill <ben.m.cahill@intel.com>
 Björn Steinbrink <B.Steinbrink@gmx.de>
+Boris Brezillon <boris.brezillon@free-electrons.com>
+Boris Brezillon <boris.brezillon@free-electrons.com> <b.brezillon.dev@gmail.com>
+Boris Brezillon <boris.brezillon@free-electrons.com> <b.brezillon@overkiz.com>
 Brian Avery <b.avery@hp.com>
 Brian King <brking@us.ibm.com>
 Christoph Hellwig <hch@lst.de>