bloblist: refactor xferlist and bloblist

bloblist: refactor xferlist and bloblist

Refactor the xferlist to remove the relocating when bloblist passed
from the boot args.
Refactor bloblist init to use incoming standard passage by default
if a valid transfer list exists in the boot args.
For bloblist relocation, use the actual total size if it has a smaller
BLOBLIST_SIZE_RELOC.

Signed-off-by: Raymond Mao <raymond.mao@linaro.org>
Suggested-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>