MAINTAINERS: adjust atomisp maintainership

From now on, I'll be maintaining the atomisp driver, and
Sakari will be reviewing it.
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

MAINTAINERS

@@ -15950,8 +15950,8 @@ S:	Supported
 F:	Documentation/process/stable-kernel-rules.rst
 
 STAGING - ATOMISP DRIVER
-M:	Alan Cox <alan@linux.intel.com>
-M:	Sakari Ailus <sakari.ailus@linux.intel.com>
+M:	Mauro Carvalho Chehab <mchehab@kernel.org>
+R:	Sakari Ailus <sakari.ailus@linux.intel.com>
 L:	linux-media@vger.kernel.org
 S:	Maintained
 F:	drivers/staging/media/atomisp/