mailmap: add linux.dev alias for Brendan Higgins

Because of my new work remote setup at Google, I can no longer use command
line tools with my google.com email address, for this reason I got a
linux.dev account.  So update the mailmap to show the new alias I will be
using.

Link: https://lkml.kernel.org/r/20220725215833.789133-1-brendan.higgins@linux.dev
Signed-off-by: Brendan Higgins <brendan.higgins@linux.dev>
Reviewed-by: David Gow <davidgow@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Daniel Latypov <dlatypov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

.mailmap

@@ -71,6 +71,7 @@ Boris Brezillon <bbrezillon@kernel.org> <b.brezillon.dev@gmail.com>
 Boris Brezillon <bbrezillon@kernel.org> <b.brezillon@overkiz.com>
 Boris Brezillon <bbrezillon@kernel.org> <boris.brezillon@bootlin.com>
 Boris Brezillon <bbrezillon@kernel.org> <boris.brezillon@free-electrons.com>
+Brendan Higgins <brendan.higgins@linux.dev> <brendanhiggins@google.com>
 Brian Avery <b.avery@hp.com>
 Brian King <brking@us.ibm.com>
 Brian Silverman <bsilver16384@gmail.com> <brian.silverman@bluerivertech.com>