.mailmap: add Christophe Ricard

Different computers had different settings in the mail client.  Some
contributions appear as Christophe Ricard, others as Christophe RICARD.
Signed-off-by: NChristophe Ricard <christophe-h.ricard@st.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

.mailmap

@@ -33,6 +33,7 @@ Björn Steinbrink <B.Steinbrink@gmx.de>
 Brian Avery <b.avery@hp.com>
 Brian King <brking@us.ibm.com>
 Christoph Hellwig <hch@lst.de>
+Christophe Ricard <christophe.ricard@gmail.com>
 Corey Minyard <minyard@acm.org>
 Damian Hobson-Garcia <dhobsong@igel.co.jp>
 David Brownell <david-b@pacbell.net>