configs: rockchip: Drop TPL_MAX_SIZE definition

The max size is defined at architectural level. On the same commit
I have checked mostly all the other architecture and look like they are

Fixes: commit ca8a329a ("Convert CONFIG_SPL_PAD_TO et al to Kconfig")
Signed-off-by: Michael Trimarchi <michael@amarulasolutions.com>
Reviewed-by: Tom Rini <trini@konsulko.com>