radeon: misc corrections

I have a new PCI-E radeon RV380 series card (PCI device ID 5b64) that
hangs in my sparc64 boxes when the init scripts set the font.  The problem
goes away if I disable acceleration.

I haven't figured out that bug yet, but along the way I found some
corrections to make based upon some auditing.

1) The RB2D_DC_FLUSH_ALL value used by the kernel fb driver
   and the XORG video driver differ.  I've made the kernel
   match what XORG is using.

2) In radeonfb_engine_reset() we have top-level code structure
   that roughly looks like:

	if (family is 300, 350, or V350)
		do this;
	else
		do that;
	...
	if (family is NOT 300, OR
	    family is NOT 350, OR
	    family is NOT V350)
		do another thing;

   this last conditional makes no sense, is always true,
   and obviously was likely meant to be "family is NOT
   300, 350, or V350".  So I've made the code match the
   intent.

Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Tested-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>