mailmap: add entry for Mike Rapoport

Add an entry to correct my email addresses.
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200708095414.12275-1-rppt@kernel.orgSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

.mailmap

@@ -198,6 +198,9 @@ Maxime Ripard <mripard@kernel.org> <maxime.ripard@free-electrons.com>
 Mayuresh Janorkar <mayur@ti.com>
 Michael Buesch <m@bues.ch>
 Michel Dänzer <michel@tungstengraphics.com>
+Mike Rapoport <rppt@kernel.org> <mike@compulab.co.il>
+Mike Rapoport <rppt@kernel.org> <mike.rapoport@gmail.com>
+Mike Rapoport <rppt@kernel.org> <rppt@linux.ibm.com>
 Miodrag Dinic <miodrag.dinic@mips.com> <miodrag.dinic@imgtec.com>
 Miquel Raynal <miquel.raynal@bootlin.com> <miquel.raynal@free-electrons.com>
 Mitesh shah <mshah@teja.com>