MAINTAINERS: set up proper record for Xilinx Zynq

Setup correct zynq entry.
 - Add missing cadence_ttc_timer maintainership
 - Add zynq wildcard
 - Add xilinx wildcard

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>