datapath-windows: ovsext.inf: Add PnpLockdown to the driver info file.

While compiling with the latest WDK/SDK 10.0.26100.1, MSVC complains:
  error 1324: [Version] section should specify PnpLockdown=1 to prevent
              external apps from modifying installed driver files.

Add PnpLockdown = 1.

More information:
https://learn.microsoft.com/en-us/windows-hardware/drivers/install/inf-version-section

Signed-off-by: Alin Gabriel Serdean <aserdean@ovn.org>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>

datapath-windows/ovsext/ovsext.inf

@@ -4,6 +4,7 @@
 
 [version]
 Signature   = "$Windows NT$"
+PnpLockdown = 1
 Class       = NetService
 ClassGUID   = {4D36E974-E325-11CE-BFC1-08002BE10318}
 Provider    = %OVS%