Revert "sunxi/nand: Add support to the SPL for loading u-boot from internal NAND memory"

This reverts commit f76eba38

.

This patch did not have a full and proper copyright/S-o-b chain.

Signed-off-by: Ian Campbell <ijc@hellion.org.uk>

Conflicts:
	include/configs/sun6i.h
	include/configs/sun8i.h