rockchip/rk3399: changed printf/tf_printf for console output

The printf() isn't used by the firmware itself, just by the tools under
the ./tools/ folder. Then tf_printf will unconditionally print.
Remove the unused print_dram_status_info() function.

Change-Id: Ie699ccb54a5be9a2cbbd7b8d4193b57075a2f57a
Signed-off-by: Caesar Wang <wxt@rock-chips.com>