Revert "spl: fix entry_point equal to load_addr"

Due to the (seemingly bogus) assumption of a default
CONFIG_SYS_UBOOT_START value we will revert this change for now and
evaluate it again for the next release along with changes to
CONFIG_SYS_UBOOT_START.

This reverts commit d3e97b53.

Signed-off-by: Tom Rini <trini@konsulko.com>