zynq-zed.dtsi: Add flash chip ID and remove "quiet" from bootargs

Also set SD clock from 33.000 to 33.333 MHz (minor, but it used to be such)
I want to see the bootlog at start (for now)
Prevent error message about mismatching flash chip (expected m25p80...)
zynq.dtsi: Support card detect for SD card slot

Both boards have the CD pins assigned, so use it to make hotplug work.