Documentation/kernel-parameters.txt: document libata's ignore_hpa option

By default the kernel honors the HPA (host protected area) of hard
drives.  Using libata's ignore_hpa module option it's possible to
change this behaviour.

Document usage and options of libata.ignore_hpa in
Documentation/kernel-parameters.txt.

Signed-off-by: Michael Prokop <mika@grml.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

Documentation/kernel-parameters.txt

@@ -1115,6 +1115,10 @@ and is between 256 and 4096 characters. It is defined in the file
 			libata.dma=4	  Compact Flash DMA only 
 			Combinations also work, so libata.dma=3 enables DMA
 			for disks and CDROMs, but not CFs.
+	
+	libata.ignore_hpa=	[LIBATA] Ignore HPA limit
+			libata.ignore_hpa=0	  keep BIOS limits (default)
+			libata.ignore_hpa=1	  ignore limits, using full disk
 
 	libata.noacpi	[LIBATA] Disables use of ACPI in libata suspend/resume
 			when set.