MAINTAINERS: change Igor Mitsyanko's email address

My email address in samsung.com domain is no longer accessible, change
it to my personal gmail address.
Signed-off-by: NIgor Mitsyanko <i.mitsyanko@gmail.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

MAINTAINERS

@@ -225,7 +225,7 @@ ARM Machines
 Exynos
 M: Evgeny Voevodin <e.voevodin@samsung.com>
 M: Maksim Kozlov <m.kozlov@samsung.com>
-M: Igor Mitsyanko <i.mitsyanko@samsung.com>
+M: Igor Mitsyanko <i.mitsyanko@gmail.com>
 M: Dmitry Solodkiy <d.solodkiy@samsung.com>
 S: Maintained
 F: hw/*/exynos*