arm64: zynqmp: Remove leading 0s from mtd table for spi flashes

Warnings:
arch/arm64/boot/dts/xilinx/zynqmp-ep108.dtb: Warning
(unit_address_format): Node
/amba/spi@ff040000/spi0_flash0@0/spi0_flash0@00000000 unit name should
not have leading 0s
arch/arm64/boot/dts/xilinx/zynqmp-ep108.dtb: Warning
(unit_address_format): Node
/amba/spi@ff050000/spi1_flash0@0/spi1_flash0@00000000 unit name should
not have leading 0s

Signed-off-by: Michal Simek <michal.simek@xilinx.com>