hikey: Fix dependencies in boot_fat.uefi.img making

boot_fat.uifi.img depends on kernel, ramdisk.img and dtb file,
that are copied to out/ with PRODUCT_COPY_FILES, and it is possible
that dtb file is not copied when target is built:
out/target/product/hikey/hi6220-hikey.dtb: No such file or directory

Change-Id: Ic486e3ee5fcd40543be3697fa3498ceef7558138
Signed-off-by: Dmitry Shmidt <dimitrysh@google.com>
3 files changed