MAINTAINERS: Remove duplicated entry for ehci-zynq.c

ehci-zynq.c is assigned to Zynq and ZynqMP that's why remove one.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Link: https://lore.kernel.org/r/d97779178fa56f1c6af40f5604b0bf349002cd36.1646639027.git.michal.simek@xilinx.com