read yukon firmware

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firmware flash read spi tftp u-boot uboot yukon

# Copy firmware to mmc
setenv filesize 0x800000
sf probe
sf read ${kernel_addr} 0 ${filesize}
# Assuming mmc 1:1 is partitioned and formatted already...
ext4write mmc 1:1 ${kernel_addr} /home/root/uboot.bin ${filesize}