intelfb: Fix bug in DPLL disable

Reported in Kernel Bugzilla 9006

Fix an obvious bug in DPLL disable.
Signed-off-by: Antonino Daplas <adaplas@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/video/intelfb/intelfbhw.c

@@ -1352,7 +1352,7 @@ intelfbhw_program_mode(struct intelfb_info *dinfo,
 
 	/* turn off PLL */
 	tmp = INREG(dpll_reg);
-	dpll_reg &= ~DPLL_VCO_ENABLE;
+	tmp &= ~DPLL_VCO_ENABLE;
 	OUTREG(dpll_reg, tmp);
 
 	/* Set PLL parameters */