Update find_vulkansdk.lua

Author: waruqi

xmake/modules/detect/sdks/find_vulkansdk.lua

@@ -30,7 +30,7 @@ import("lib.detect.find_package")
 function _find_vulkan_from_paths(paths, opt)
     opt = opt or {}
     local arch = opt.arch or config.arch() or os.arch()
-    local plat = opt.plat or config.get("plat") or os.host()
+    local plat = opt.plat or config.plat() or os.host()
     local binsuffix = ((is_host("windows") and arch == "x86") and "bin32" or "bin")
     local libname = (is_host("windows") and "vulkan-1" or "vulkan")
     local libsuffix = ((is_host("windows") and arch == "x86") and "lib32" or "lib")