x86, hpet: Add reference to chipset erratum documentation for disable-hpet-msi-quirk

(At the moment the "SB700 Family Product Errata" document is available
at http://support.amd.com/us/Embedded_TechDocs/46837.pdf)

Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
LKML-Reference: <20100517164324.GB10254@alberich.amd.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

arch/x86/kernel/quirks.c

@@ -495,6 +495,9 @@ void force_hpet_resume(void)
 /*
  * HPET MSI on some boards (ATI SB700/SB800) has side effect on
  * floppy DMA. Disable HPET MSI on such platforms.
+ * See erratum #27 (Misinterpreted MSI Requests May Result in
+ * Corrupted LPC DMA Data) in AMD Publication #46837,
+ * "SB700 Family Product Errata", Rev. 1.0, March 2010.
  *
  * Also force the read back of the CMP register in hpet_next_event()
  * to work around the problem that the CMP register write seems to be