ACPI: extend "acpi_osi=" boot option

The boot option "acpi_osi=" has always disabled Linux _OSI support,
thus disabling all OS Interface strings which are advertised
by Linux to the BIOS.

Now...
acpi_osi="string" adds the interface string, and
acpi_osi="!string" invalidates the pre-defined interface string

eg. acpi_osi="!Windows 2006"
would disable Linux's claim of Vista compatibility.

Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index aae2282..7915014 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -170,7 +170,10 @@
 	acpi_os_name=	[HW,ACPI] Tell ACPI BIOS the name of the OS
 			Format: To spoof as Windows 98: ="Microsoft Windows"
 
-	acpi_osi=	[HW,ACPI] empty param disables _OSI
+	acpi_osi=	[HW,ACPI] Modify list of supported OS interface strings
+			acpi_osi="string1"	# add string1 -- only one string
+			acpi_osi="!string2"	# remove built-in string2
+			acpi_osi=		# disable all strings
 
 	acpi_serialize	[HW,ACPI] force serialization of AML methods