arm: Use CONFIG_SPL_STACK or CONFIG_SYS_INIT_SP_ADDR directly.

arm: Use CONFIG_SPL_STACK or CONFIG_SYS_INIT_SP_ADDR directly.

In some cases, we define CONFIG_SYS_INIT_SP_ADDR differently for SPL or
full U-Boot.  This case should be making use of CONFIG_SPL_STACK, as
that's what that variable is for.  In a few other cases we define
CONFIG_SPL_STACK directly to CONFIG_SYS_INIT_SP_ADDR, but do not need to
as the code handles this correctly, normally.

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