This patch adds accelerated copyarea and sets READS_FAST flag.
This doubles scrolling speed on SparcStation20 85MHz.

It also fixes a comment in cg6_fillrect function.
Signed-off-by: NKrzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>