fdt: check fdt_pack() return value in fdtdec_apply_bloblist_dtos()

fdt: check fdt_pack() return value in fdtdec_apply_bloblist_dtos()

The fdt_pack() function can return an error code, but its return value
was not being checked. Add proper error handling to propagate any
failure.

Also fix typo in comment: "Shink" -> "Shrink".

Addresses-Coverity-ID: CID 645839: Error handling issues (CHECKED_RETURN)
Signed-off-by: Michal Simek <michal.simek@amd.com>
Reviewed-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Raymond Mao <raymondmaoca@gmail.com>