video: make BPP and ANSI configs optional

Many boards do not use all selected framebuffer depth
configurations, for such boards there is some unused
code in video and console uclass routines. Make depth
specific code optional to avoid dead code and slightly
reduce binary size. Also make ANSI code optional for
the same reason. When i.e. using only VIDEO_BPP16 the
code size shrinks (below values when using gcc-7.3.0):

  $ ./tools/buildman/buildman -b video-wip -sS wandboard
  ...
  01: Merge git://git.denx.de/u-boot-sh


  02: video: add guards around 16bpp/32bbp code
  03: video: make BPP and ANSI configs optional
         arm: (for 1/1 boards) all -776.0 bss -8.0 text -768.0

Signed-off-by: Anatolij Gustschin <agust@denx.de>
Tested-by: Eugen Hristev <eugen.hristev@microchip.com>
Tested-by: Patrice Chotard <patrice.chotard@st.com>
Tested-by: Steffen Dirkwinkel <s.dirkwinkel@beckhoff.com>