Update Paul Burton's email address

MIPS is no longer a part of Imagination Technologies, and as such my
@imgtec.com email address will soon cease to function. This patch
updates occurrances of it with my new @mips.com email address, and adds
an entry in .mailmap such that git (& tools such as get_maintainer.pl
when examining history) will use the new address.

Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Cc: u-boot@lists.denx.de
diff --git a/board/imgtec/malta/superio.h b/board/imgtec/malta/superio.h
index 271c462..f0ae142 100644
--- a/board/imgtec/malta/superio.h
+++ b/board/imgtec/malta/superio.h
@@ -1,6 +1,6 @@
 /*
  * Copyright (C) 2013 Imagination Technologies
- * Author: Paul Burton <paul.burton@imgtec.com>
+ * Author: Paul Burton <paul.burton@mips.com>
  *
  * Setup code for the FDC37M817 super I/O controller
  *