boot: android: Always use 8-byte aligned DT with libfdt

Newer versions of libfdt strictly check whether the FDT blob
passed to them is at 8-byte aligned offset, if it is not, then
the library fails checks with -FDT_ERR_ALIGNMENT . Currently,
android_image_print_dtb_contents() passed FDT directly mapped
from abootimg to libfdt, and this FDT is not always aligned to
8-byte offset. Specifically, the FDTs are somewhat packed in
the abootimg, therefore if the first FDT blob is e.g. 0xfd bytes
long, then the next FDT blob ends up at 0xfd offset, which is
not 8-byte aligned.

Fix this by first extracting the header into 8-byte aligned buffer,
checking only the header for validity, and then by copying the
entire FDT into newly allocated 8-byte aligned buffer. While this
is not efficient, it is the correct way to handle DTs, which must
be at 8-byte aligned offsets. Mitigate the inefficiency for the
common case by checking whether the DT might be 8-byte aligned and
if it is, map it directly.

Signed-off-by: Marek Vasut <[email protected]>
Reviewed-by: Mattijs Korpershoek <[email protected]>
Reviewed-by: Tom Rini <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Mattijs Korpershoek <[email protected]>

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