media: MAINTAINERS: Update reviewers for ipu3-cio2

Remove Jian Xu from the driver's reviewers.
Signed-off-by: NSakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab+samsung@kernel.org>

MAINTAINERS

@@ -7696,7 +7696,6 @@ M:	Yong Zhi <yong.zhi@intel.com>
 M:	Sakari Ailus <sakari.ailus@linux.intel.com>
 M:	Bingbu Cao <bingbu.cao@intel.com>
 R:	Tian Shu Qiu <tian.shu.qiu@intel.com>
-R:	Jian Xu Zheng <jian.xu.zheng@intel.com>
 L:	linux-media@vger.kernel.org
 S:	Maintained
 F:	drivers/media/pci/intel/ipu3/