[TGAFB] implement the imageblit acceleration hook

[Richard Henderson]

Please pull from

	bk://are.twiddle.net/tgafb-2.5

r~

 drivers/video/tgafb.c |  255 +++++++++++++++++++++++++++++++++++++++++++++++++-
 include/video/tgafb.h |   27 +++++
 2 files changed, 281 insertions, 1 deletion

through these ChangeSets:

<[e-mail]> (02/12/31 1.954.2.7)
   [TGAFB] Implement the fb_imageblit hook.
   
   Speeds up rendering of text by around 7x for 8bpp cards,
   as you'd expect from the difference in the volume of data
   passed across the bus.  Thus the win should be about 31x
   for 32bpp cards.