.mailmap: Start to use new amd.com email address

Xilinx has been acquired by AMD that's why emails should be also updated.
The patch is updating .mailmap file and also MAINTAINERS files as was done
by commit 5cd1ecb99490 ("ppc: qemu: Update MAINTAINERS for correct email
address").
The rest of my emails are not going to change.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@amd.com>
diff --git a/.mailmap b/.mailmap
index 1f88ea9..3910e05 100644
--- a/.mailmap
+++ b/.mailmap
@@ -43,6 +43,7 @@
 Markus Klotzbuecher <mk@denx.de>
 Masahiro Yamada <yamada.masahiro@socionext.com> <yamada.m@jp.panasonic.com>
 Masahiro Yamada <yamada.masahiro@socionext.com> <masahiroy@kernel.org>
+Michal Simek <michal.simek@amd.com> <michal.simek@xilinx.com>
 Michal Simek <michal.simek@xilinx.com> <monstr@monstr.eu>
 Michal Simek <michal.simek@xilinx.com> <Monstr@seznam.cz>
 Michal Simek <michal.simek@xilinx.com> <root@monstr.eu>