spl: Allow tiny printf() to be controlled in SPL and TPL

At present there is only one control for this and it is used for both SPL
and TPL. But SPL might have a lot more space than TPL so the extra cost of
a full printf() might be acceptable.

Split the option into two, providing separate SPL and TPL controls. The
TPL setting defaults to the same as SPL.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>