scripts: Fix xlib_xrandr platform name

Change-Id: I3aa8e929d394322ebfcfbf2a59846b2adae057e3
diff --git a/scripts/common_codegen.py b/scripts/common_codegen.py
index 7319c01..8662a6f 100644
--- a/scripts/common_codegen.py
+++ b/scripts/common_codegen.py
@@ -58,7 +58,7 @@
     'win32' : 'VK_USE_PLATFORM_WIN32_KHR',
     'xcb' : 'VK_USE_PLATFORM_XCB_KHR',
     'xlib' : 'VK_USE_PLATFORM_XLIB_KHR',
-    'xlib_randr' : 'VK_USE_PLATFORM_XLIB_RANDR_EXT',
+    'xlib_xrandr' : 'VK_USE_PLATFORM_XLIB_XRANDR_EXT',
 }
 
 #