nb/intel/gm45: Fix panel-power-sequence clock divisor

We kept this value at it's default on the native graphics init path.
Maybe the Video BIOS path, too, I don't know if the VBIOS sets it.

The panel power sequencer uses the core display clock (CDCLK). It's
based on the HPLLVCO and a frequency selection we made during raminit.
The value written is the (actual divisor/2)-1 for a 100us timer.

v2: Fix unaligned mmio access inherited from Linux.

v3: Use MCHBAR8() instead. Also, the unaligned access might have
    worked after all.

Change-Id: I877d229865981fb0f96c864bc79e404f6743fd05
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/17619
Tested-by: build bot (Jenkins)
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
diff --git a/src/northbridge/intel/gm45/gm45.h b/src/northbridge/intel/gm45/gm45.h
index ae1863b..b9d2cb7 100644
--- a/src/northbridge/intel/gm45/gm45.h
+++ b/src/northbridge/intel/gm45/gm45.h
@@ -260,6 +260,8 @@
 #define MCHBAR16(x) *((volatile u16 *)(DEFAULT_MCHBAR + x))
 #define MCHBAR32(x) *((volatile u32 *)(DEFAULT_MCHBAR + x))
 
+#define HPLLVCO_MCHBAR		0x0c0f
+
 #define PMSTS_MCHBAR		0x0f14	/* Self refresh channel status */
 #define PMSTS_WARM_RESET	(1 << 1)
 #define PMSTS_BOTH_SELFREFRESH	(1 << 0)