matroxfb: fix problems with display stability

Regression caused in 2.6.23 and then despite repeated requests never fixed
or dealt with (Petr promised to sort it in 2008 but seems to have
forgotten).

Enough is enough - remove the problem line that was added.  If it upsets
someone they've had two years to deal with it and at the very least it'll
rattle their cage and wake them up.

Addresses http://bugzilla.kernel.org/show_bug.cgi?id=9709

Signed-off-by: Alan Cox <alan@linux.intel.com>
Reported-by: Damon <account@bugzilla.kernel.org.juxtaposition.net>
Tested-by: Ruud van Melick <rvm1974@raketnet.nl>
Cc: Petr Vandrovec <VANDROVE@vc.cvut.cz>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Paul A. Clarke <pc@us.ibm.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/video/matrox/g450_pll.c

@@ -368,7 +368,8 @@ static int __g450_setclk(struct matrox_fb_info *minfo, unsigned int fout,
 					M1064_XDVICLKCTRL_C1DVICLKEN |
 					M1064_XDVICLKCTRL_DVILOOPCTL |
 					M1064_XDVICLKCTRL_P1LOOPBWDTCTL;
-				matroxfb_DAC_out(minfo, M1064_XDVICLKCTRL, tmp);
+                                /* Setting this breaks PC systems so don't do it */
+				/* matroxfb_DAC_out(minfo, M1064_XDVICLKCTRL, tmp); */
 				matroxfb_DAC_out(minfo, M1064_XPWRCTRL,
 						 xpwrctrl);