tpl: Kconfig: TPL_BANNER_PRINT depends on DEBUG_UART && TPL_SERIAL

As implemented in the arch/arm/mach-rockchip/tpl.c file,
the CONFIG_TPL_BANNER_PRINT option will not work
if either of these options is not enabled.

Add dependency constraints to the CONFIG_TPL_BANNER_PRINT option
definition to prevent configuration problems
where option is enabled but do not take effect.

Suggested-by: Yanjie Ren <renyanjie01@gmail.com>
Signed-off-by: Ying Sun <sunying@nj.iscas.ac.cn>