x86/platform/uv: Update sysfs documentation

Update sysfs documentation file to include moved /proc leaves.
Signed-off-by: Mike Travis <mike.travis@hpe.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lkml.kernel.org/r/20201128034227.120869-6-mike.travis@hpe.com

Documentation/ABI/testing/sysfs-firmware-sgi_uv

@@ -7,10 +7,25 @@ Description:
 
 		Under that directory are a number of read-only attributes::
 
+			archtype
+			hub_type
+			hubless
 			partition_id
 			coherence_id
 			uv_type
 
+		The archtype entry contains the UV architecture type that
+		is used to select arch-dependent addresses and features.
+		It can be set via the OEM_ID in the ACPI MADT table or by
+		UVsystab entry both passed from UV BIOS.
+
+		The hub_type entry is used to select the type of hub which is
+		similar to uv_type but encoded in a binary format.  Include
+		the file uv_hub.h to get the definitions.
+
+		The hubless entry basically is present and set only if there
+		is no hub.  In this case the hub_type entry is not present.
+
 		The partition_id entry contains the partition id.
 		UV systems can be partitioned into multiple physical
 		machines, which each partition running a unique copy
@@ -24,6 +39,7 @@ Description:
 
 		The uv_type entry contains the hub revision number.
 		This value can be used to identify the UV system version::
+			"0.*" = Hubless UV ('*' is subtype)
 
 			"3.0" = UV2
 			"5.0" = UV3