mailmap: Update name spelling and email for Dengcheng Zhu

Change my first name spelling from Deng-Cheng to Dengcheng.

Update email addresses.
Signed-off-by: Dengcheng Zhu <dzhu@wavecomp.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@linux-mips.org

.mailmap

@@ -47,7 +47,10 @@ Corey Minyard <minyard@acm.org>
 Damian Hobson-Garcia <dhobsong@igel.co.jp>
 David Brownell <david-b@pacbell.net>
 David Woodhouse <dwmw2@shinybook.infradead.org>
-Deng-Cheng Zhu <dengcheng.zhu@mips.com> <dengcheng.zhu@imgtec.com>
+Dengcheng Zhu <dzhu@wavecomp.com> <dengcheng.zhu@mips.com>
+Dengcheng Zhu <dzhu@wavecomp.com> <dengcheng.zhu@imgtec.com>
+Dengcheng Zhu <dzhu@wavecomp.com> <dczhu@mips.com>
+Dengcheng Zhu <dzhu@wavecomp.com> <dengcheng.zhu@gmail.com>
 Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
 Domen Puncer <domen@coderock.org>
 Douglas Gilbert <dougg@torque.net>