MAINTAINERS: Update Lukasz Luba's email address

Update Lukasz Luba's email address to @arm.com in MAINTAINERS and map it
correctly in .mailmap file.

Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
diff --git a/.mailmap b/.mailmap
index c24773d..6adff2d 100644
--- a/.mailmap
+++ b/.mailmap
@@ -152,6 +152,7 @@
 Linus Lüssing <linus.luessing@c0d3.blue> <linus.luessing@ascom.ch>
 Li Yang <leoyang.li@nxp.com> <leo@zh-kernel.org>
 Li Yang <leoyang.li@nxp.com> <leoli@freescale.com>
+Lukasz Luba <lukasz.luba@arm.com> <l.luba@partner.samsung.com>
 Maciej W. Rozycki <macro@mips.com> <macro@imgtec.com>
 Marc Zyngier <maz@kernel.org> <marc.zyngier@arm.com>
 Marcin Nowakowski <marcin.nowakowski@mips.com> <marcin.nowakowski@imgtec.com>