rockchip: defconfig: puma-rk3399: update defconfig with video-support

With HDMI output for the RK3399 working, this update the RK3399-Q7
(Puma) defconfig for the new functionality:
1. enables PMIC command (to check if the HDMI voltages are correct)
      +CONFIG_CMD_PMIC=y
      +CONFIG_CMD_REGULATOR=y
2. enables video-output (via HDMI)
      +CONFIG_DM_VIDEO=y
      +CONFIG_DISPLAY=y
      +CONFIG_VIDEO_ROCKCHIP=y
      +CONFIG_DISPLAY_ROCKCHIP_HDMI=y
3. turns on the 'dcache'-command (for a dcache flush) for our QA to
   fill the framebuffer using 'mw.l'
      +CONFIG_CMD_CACHE=y
4. turns on the 'bmp'-command
      +CONFIG_CMD_BMP=y

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Acked-by: Simon Glass <sjg@chromium.org>