MAINTAINERS, .mailmap: update Umang's email address

Map my new professional email address in .mailmap and also update
the IMX283 driver entry with the same.

At the same time, update my role to a reviewer for the IMX283 driver.

Link: https://lkml.kernel.org/r/20250929074025.84407-1-uajain@igalia.com
Signed-off-by: Umang Jain <uajain@igalia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: Umang Jain

.mailmap

@@ -803,6 +803,7 @@ Tvrtko Ursulin <tursulin@ursulin.net> <tvrtko.ursulin@onelan.co.uk>
 Tvrtko Ursulin <tursulin@ursulin.net> <tvrtko@ursulin.net>
 Tycho Andersen <tycho@tycho.pizza> <tycho@tycho.ws>
 Tzung-Bi Shih <tzungbi@kernel.org> <tzungbi@google.com>
+Umang Jain <uajain@igalia.com> <umang.jain@ideasonboard.com>
 Uwe Kleine-König <ukleinek@informatik.uni-freiburg.de>
 Uwe Kleine-König <u.kleine-koenig@baylibre.com> <ukleinek@baylibre.com>
 Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

MAINTAINERS

@@ -23882,7 +23882,7 @@ F:	drivers/media/i2c/imx274.c
 
 SONY IMX283 SENSOR DRIVER
 M:	Kieran Bingham <kieran.bingham@ideasonboard.com>
-M:	Umang Jain <umang.jain@ideasonboard.com>
+R:	Umang Jain <uajain@igalia.com>
 L:	linux-media@vger.kernel.org
 S:	Maintained
 T:	git git://linuxtv.org/media.git