arm64: zynqmp: Setup multiboot register to 0

On Kria when board starts from Image A or Image B partition multiboot
register is already setup to that location. When reset command is called
board is issuing soft reset which start SW at already used location (offset
of multiboot * 32k).
But board should continue to run from multiboot offset 0 (start of QSPI)
and call early bootloader every reboot that's why clear multiboot register
to 0 by default to go that route all the time.

Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/edaf714a778bdd7447533a77b3455e4fd623f9da.1717420131.git.michal.simek@amd.com

board/xilinx/zynqmp/zynqmp_kria.env

@@ -65,6 +65,7 @@ kd240_setup=i2c dev 1 && run usb_hub_init;zynqmp pmufw node 33; zynqmp pmufw nod
 tpm_setup=tpm autostart;
 
 board_setup=\
+zynqmp mmio_write 0xFFCA0010 0xfff 0; \
 if test ${card1_name} = SCK-KV-G; then run kv260_setup; fi;\
 if test ${card1_name} = SCK-KR-G; then run kr260_setup; fi;\
 if test ${card1_name} = SCK-KD-G; then run kd240_setup; fi;\